Well, taking back capture moves is implemented for all Fidelity modules, just look at the file 'Info_Fidelity.txt' - there's even a special section about how to do this!

As for the other problem: I think one can expect that the user takes care of not making nonsense moves (like the example you have described). For my first programmed modules (the Elite Avantgarde) there is indeed the possibility to correct such wrong 'moves', and this can be done with the small border pieces: whenever a board square is selected (i.e. the LED is ON), you can choose any border piece and put it on this board square.

But implementing this feature was really a lot of work, so I was not keen on writing such a (quite long) code for all the other numerous Fidelity engines.

Franz