My suggestion.

escritura pública de protocolización del pacto social y de las reformas = document of public record for recording articles of incorporation and any amendments

Don't use "public DEED"; use "document of public record". At least in the USA, a "deed" is only for conveyance of real property, nothing else.

“instrument” covers all kinds of documents and removes the connotations of sealing (even though a deed no longer needs sealing and must be ‘signed as a deed’) which attach to deeds (and deeds are usually synallagmatic whereas in so many cases attested documents involve only one person and create no reciprocal obligations).

It would be illuminating to have a discussion about bylaws/articles of incorporation/memorandum of association/articles of association/ statutes etc.

The EU institutions have gone for “statutes” in most cases (see for example: ECJ Case C-426/98. “Failure by a Member State to fulfil its obligations - Directive 69/335/EEC - Indirect taxes on the raising of capital - Special charges imposed on the formation of public and private limited liability companies, on the publication and alteration of their statutes and on the increase in their capital.”)

On the other hand, in the ECJ Rules of Procedure (Art. 38) the term chosen is “constituting”:
“5. An application [to the Court] made by a legal person governed by private law shall be accompanied by …the instrument or instruments constituting or regulating that legal person or a recent extract from the register of companies, firms or associations or any other proof of its existence in law …”

This reflects the age-old problem of the EN law approach of setting out the objects in the memorandum of association and other provisions in the articles of association (so that neither term alone tells the whole story – so the decision was taken in about 1971 to skate round the problem when the ECJ English version of the Rules of Proc was drawn up.