A couple of thoughts...

You could just not bother to (directly) incentivize language suggestions. I'll continue to toss them out there because it makes the predictions more playable. That's enough reward for me.

If you DID want to then just have the editors be able to toss S$5,000 to the first person to post a suggestion/improvement which the editor incorporates into an accepted suggestion. Perhaps it could be an editor's discretion type of thing. If it's a significant contribution then it gets the additional award, otherwise it's just a minor tweak and we carry on as now.

If you want to incentivize proper suggestion creation in the first place, have the S$5,000 come out of the S$25,000 bounty for an accepted suggestion.

I'd favor it being an additional award, with no cost to the suggester, but that does somewhat allow people to continue being sloppy when they first set suggestions up.

Gets a bit harder if you start allowing users (even a select group of non-staffers) edit directly.