In this context I do not believe that “finca hipotecaria” means “mortgaged property” (which is usually expressed as “finca hipotecaDA”). Here I suspect that “hipotecaria” refers to the fact that the property (land, parcel, etc.) has been recorded (and given a number) on the Land (or) Real Property Register (“Registro de la Propiedad”). Thus, your text makes reference to “finca hipotecaria xx” ("xx" being the number assigned to the property on the Register), likewise including the number of the “folio” and “libro” where the property is recorded. In my interpretation, in your text "finca hipotecaria" means "finca registral".

I think I’m on the right track here and, just for info, I’m copying below an entry in my blog on Spanish-English legal terminology in which I discuss instances in which the adjectives “hipotecario” and “hipotecaria” do not refer to “mortgages.”

"Derecho hipotecario;" "Ley hipotecaria"

Translators unfamiliar with Spanish law often automatically assume that the adjectives "hipotecario" and "hipotecaria" refer exclusively to mortgages ("hipotecas"). Thus there is an assumption that "Derecho hipotecario" is limited to “mortgage law” and that "Ley hipotecaria" refers to legislation specifically governing mortgages, and these mistakes have found their way into several bilingual legal dictionaries. Although traditionally called "Derecho hipotecario," in Spain this branch of law actually concerns the registration of rights in real property on the Land Register ("Registro de la Propiedad"). The fact that "Derecho hipotecario" is a misnomer (and that "Derecho inmobiliario registral" is a more accurate term) has been recognized in several Spanish legal sources. Luis Ribó Durán in his "Diccionario de Derecho" (Bosch, 2005) explains that “Derecho hipotecario es la parte del Derecho que estudia la adquisición, transmisión, modificación y extinción de los derechos sobre bienes inmuebles en cuanto éstos se reflejan en el Registro de la Propiedad. (…) La denominación Derecho inmobiliario registral, posiblemente la más adecuada, ha sido muchas veces postergada ante la de Derecho hipotecario, de más rancia tradición al enlazar con el nombre de la ley especial que, antes de la promulgación del vigente Código Civil, desmarcó de éste la materia inmobiliaria registral…”.

Likewise, in its article on “Derecho inmobiliario registral,” the "Gran Enciclopedia Rialp" (1991) notes that “generalmente, entre los autores españoles, se llama ‘Derecho hipotecario,’ denominación que obedece al título de la ley que regula la materia, la Ley Hipotecaria. Es claro que el nombre de la ley no responde a su contenido, pues en ella se regula, además de la hipoteca, todo referente al Registro de la Propiedad.” Thus, rendering "Derecho hipotecario" as “mortgage law” is misleading, while a translation that accurately reflects the true content of this legal discipline in Spain might be “Law of Land (or) Real Estate Registration” or “Land (or) Real Estate Registration Law,” etc. (The "Registro de la Propiedad" for England and Wales is called the “Land Registry.” There is no centralized land register for real property in the US where real estate is recorded in the state where it is located.)

Similarly, "Ley Hipotecaria" cannot really be appropriately translated as “Mortgage Act,” as it is often rendered. Although as indicated above, Articles 104-197 of the "Ley Hipotecaria" deal with mortgages per se, the remaining 329 articles regulate land registration and determine how the property registry ("Registro de la Propiedad") is to be organized and the duties of property registrars ("Registradores de la Propiedad"). Thus, in this case "Ley Hipotecaria" might be more properly translated as “Land Registration Act” or “(Real) Property Registration Act,” while there are other laws that might indeed be accurately described as “mortgage acts,” such as the "Ley del Mercado Hipotecario" (“Mortgage Market Act”).

In other respects, the expression "Distrito Hipotecario," sometimes rendered as “Mortgage District,” actually refers to a “land (or) property tax district.” And "Oficina Liquidadora del Distrito Hipotecario" denotes a “district land (or) property tax office” in charge of collecting transfer taxes and stamp duties levied on the transfer of real property and other transactions ("impuestos sobre transmisiones patrimoniales y actos jurídicos documentados"), as well as inheritance and gift taxes ("impuestos sobre sucesiones y donaciones").
https://rebeccajowers.com/2016/03/14/mistranslations-1/


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Note added at 10 hrs (2018-06-20 10:31:09 GMT)
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To address Toni's comment:

The fact that these properties actually have a "folio" and/or "libro" number suggests that they have already been registered/recorded and can be found under the numbers ("xx") that have been redacted from the text on the "folios" and in the "libros" indicated. It is my understanding that for privacy reasons the numbers have been redacted and replaced with "xx". Thus,

finca hipotecaria xx = property registered/recorded under number xx
folio xx = folio number xx
libro xx = book number xx

In contrast, I believe the Spanish term most often used for properties that are "recordable/registrable" (property that, as Toni suggests, is not yet registered but that may be recorded in the future) is "inscribible".

Examples of how "inscribible is used with the meaning of "recordable/registrable" can be found in this definition from the "Diccionario del español jurídico:
http://dej.rae.es/#/entry-id/E9290



acto inscribible--
finca hipotecaria xx = property registered/recorded under number xx
folio xx = folio number xx
libro xx = book number xx

Moreover, in Spanish the term most often used to refer to a property that is "recordable/registrable" is "inscribible" rather than



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Note added at 10 hrs (2018-06-20 10:54:53 GMT)
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(Sorry for the repeated text hanging at the end my entry above--I couldn't see what was left in the window!)

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Note added at 14 hrs (2018-06-20 14:54:16 GMT)
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One of the first things that Spanish civil law professors point out to their students of "Derecho hipotecario" is that the expression is synonymous with to "Derecho inmobiliario registral", the law governing the registration of real property and that, in this context "hipotecario" does not refer to "mortgages":

Derecho Hipotecario equivale a Derecho Inmobiliario Registral; y si recibe el primer nombre no es porque estudie el derecho real de hipoteca (que también lo hace), sino por haber nacido históricamente para llenar la necesidad de dar publicidad a las cargas y afecciones reales sobre las fincas (y especialmente a las hipotecas), la clandestinidad de las cuales o su carácter oculto perjudicaba notablemente el tráfico inmobiliario.
http://cv.uoc.edu/tren/trenacc/web/GAT_EXP.PLANDOCENTE?any_a...

El derecho inmobiliario registral es el derecho hipotecario; aquél que estudia la organización, funcionamiento y eficacia del Registro de la Propiedad. Es el conjunto de normas que regulan el Registro de la Propiedad como oficina, el funcionamiento del Registro de la Propiedad y los efectos derivados de los asientos registrales.
https://unybook.com/apuntes/file-84572958cc9ed4757faee15474c...

Estudio sobre el concepto del Derecho llamado «inmobiliario» o «hipotecario». Plantea el problema de la imprecisión de las definiciones, y con este motivo trata: ... La denominación más adecuada; a juicio del autor, lo es la de «Derecho inmobiliario registral».
https://books.google.es/books?id=GGUJAAAAIAAJ