Hi! If you could share the characters/stage with me I'd love to take a look and see if I can fix the transparency issues or if I can find a workaround! Can't really see what's going wrong from the screenshots by themselves unfortunately, my best guess would be that it might be some sff texture type that was unsupported.
Widescreen support wasn't really on the agenda yet (due to the Dreamcast focus), but I'll keep it in mind! It would definitely make the Vita version look a lot better, non-widescreen Dolmexica always looks a little strange on there when it's stretched (or cropped as it was before). Hope I can get a first version of it working for the next release.
Thanks a lot for the suggestion and for taking the time to share the bug with me, hope I can get it fixed!