Sadly, it is not possible to assess the authenticity of the document central to the Tallano claim of ownership of the entire archipelago of the Philippines. It has never been submitted in court proceedings, there is no image of it in court filings and it has never been studied by historians or forensic document analysts. Although an addendum to the 1965 translation says it is authentic it is unclear what ‘authentic’ means in this case. It may mean that the translation entered into court is an authentic copy of what was entered into court, it may mean the original document upon which the translation is based is authentic. In other words, the certification is so ambiguous that it is meaningless.
Given the importance of the document, one would expect the presence of at least one, if not two, expert witnesses. For instance, a statement under oath by a historian familiar with the period who confirms that the information given in the document is congruent with what is know about the period, and by a document examiner confirming, under oath, that the substrate, what the document was written on, and the inks used to write it, and the signatures on the document broadly match known examples of those who are alleged to have signed it. No expert witnessed were consulted on the authenticity of the document. No court asked for such witnesses.
Here is all we know about the document is this:
Being almost beyond readability is not an excuse to deny the court sight of the document. Even back in the 1960s, there were means of extracting information from damaged documents using infra-red and ultra-violet light. Given the lack of readability, it is surprising that there is no assurance given under oath with regard to the accuracy of the translation.
An inadequate translation might explain some of the fluffs made it the translation document but cannot explain the many glaring anachronisms dotted throughout it.
Here is the alleged translation. Feel free to identify those points that show it to be fraudulent or those that indicated that it is genuine in the comments below.