I'm off onto a new tangent: a TMX manipulation module. I still don't have a fantastic API for it, but you know, I think I'm going to dump the xmlapi for real now. It's been 12 years now and I think it's time to move on. So I'm going to rewrite File::TTX to work with a different XML library (probably XML::Reader/XML::Writer) and do the same with TMX. This will allow me to choose between loading the file into memory in toto, or just writing a stream processor to filter things out on the fly for really large files.
I envision an overarching Xlat::TM API that will work with File::TMX in specific, and perhaps with others if and when.