It'll work just fine on the Touch Pro (there are a number of people using it on the Touch Diamond, which has the same resolution), but I'm not so sure about the Xperia, I understand there were some problems with the emulator, so unless Pleco has got an actual device with that resolution you might be out of luck with that for the moment. However, it will work eventually. I'm not just sure if it already does so .
I just picked up the Xperia X1 and Pleco works like a charm with it. There are some apps that will struggle with it a bit, if you look on the xda forums there is an app you can download which will force the screen into VGA or QVGA mode.