Unless there is element of fraud than perhaps there will be problem, otherwise your SNP is good.

Many people including lawyers seem to have a view that agreement stamp means its valid, based on case law and my research (if ur interested to know), stamping of agreement has two effects:

First, it enables admission of document into court ( that doesn't mean its valid, it just say OK this fella has observed stamping requirements).

Secondly, court recognize that stamping is a source of revenue  for the government. The government is smart enough to add a barrier a force ppl to stamping their agm before it is allowed to be admitted into court.

I don't your loan lawyer will touch it, coz its not a document prepared by them. It's best u go back to your SNP lawyer and ask them to rectify it. It's very negligent of them as the document preparer but did not advise you on the signning requirements.