Modified AdobeViewer is probably a no go, because adobeviewer is setuid (sreader). It appears all protected stuff is under that account, including text to speech and dictionary.
As for Del, I'm not even sure what device had such a button. It's certainly possible to rebuild poterm to use some other button. The tty message is probably from poterm using pipes rather than pseudottys, which would take a bit more work to fix. I haven't adapted poterm, just built it unmodified.
FBreader180 is probably a matter of just building, though I am not sure if it can access the dictionaries then. There's also a risk it needs some work for the accelerometer, if they changed the API for that.
Worst case scenario, the inkview library has had incompatible structure changes (it has happened before, with the settings interface), and this build system will be crippled compared to the (as yet unavailable) SDK.