Hi,
I used to use the BFG data files a while ago but I stopped playing, however I decided to pop in to see what was happening. It's great to see someone taking up the banner as I wouldn't like to see the end of the BFG datafiles for other players!
Just a quick note, and I don't know if you've already sorted it, but a solution to the unable to open files with developer turned on is fairly straightforward (and as far as I can see without repercussions).
Go to the BFG.def definition file, unit stat tab and change both the armour and speed lower bounds to -4 (armour) and -7 (speed), which are technically both the lower bounds. That gets rid of all the errors on loading
Hope this is useful to you, I might be interested in doing some coding or something, though i'll admit now i'm not the greatest!
p.s. also could a decision be made on whether to end sentences with full stops or not in rules/throughout? Cheers