Yes, unfortunately this is a bug with the gtk widgets running on Maemo 5. I don't think I can fix it. Luckily, the on-screen keyboard works properly, and even if you must struggle with the hardware keyboard, you normally will not need to re-enter your height and traget weight very often.
Hmmm - I've not seen that. Could you email me the contents of the settings file and data file (orrery.moko@gmail.com) so I can try to reproduce the bug and fix it (feel free to change the weight and height data!) ? Also, if you can dump your data from WeightJinni, I can convert it to the format that maeFat uses, and send it back to you.