I have not looked at the games myself, at least not from this perspective, but given the amount of code recycling they tend to involve I would be surprised if you can't just copy and paste the newer font format over the older one. If you can operate anything that handles DS ROMs (ndstool, dslazy/dsbuff, tinke, crystaltile2...) you can give it a try.
It might be that you need to actually hack things in the end but definitely worth trying this as a first pass.