I don’t know what to tell you dude. A certified or digitally can’t/wont be read by OCR. A digitally signed document legally certifies that the document has not been modified. PDF editors such as Bluebeam or Adobe will not or cannot process a certified or digitally signed document.

I’m not sure if that limitation is due to the process by which the document is certified or if it is a feature of software conforming for legality reasons. I’m not going to research this for OP, I’m just providing a simple and best accurate answer.

Maybe current AI has better abilities to process document text? I’m not sure, maybe. But you’d think this would be a shared concern with groups wanting to protect documents for the same reason and therefore encryption would match.

If it’s just the legality of it stopping a company from providing the feature, you would think most companies would want to keep out of legal hot water and would then disallow OCR processing. In this case sure there could be software that doesn’t conform, but for most application purposes I don’t think you’d have to worry too much.