Hiya, yes indeed, when I get the chance I hope to investigate further refinements to the available keyboard mapping.
At the moment click does not map to an Rg350 physical key, this is a holdover from the Gp2X original.
I hope (with the next release BeebEm for RG350 0.6.3) to move current L1 and R1 buttons to maybe L2 and R2 respectively, and to also add the start button to available buttons to map, thus giving another 3 buttons to readily use during games or on game menu screens. (Maybe even look into the analogue sticks too next, not sure how easy they are to map) (not started looking at this release yet, real life gets in the way (happy to look at pull requests on github for any other contributors))
Glad you are having fun with Frak and Chuckie Egg. Another tip for Chuckie Egg, if you go to game options and select video:centered, it looks a bit better imho.
I am also going through a few of the most popular games and creating keyboard mapping files, hope to put them on my site, so that most games can be played straight away, with dpad used for directions and B for jump and A for fire. I will update this thread with any updates.
Thanks for the feedback, and any more suggestions gratefully received