I'm not such a good programmer.
Since FOnline maps are enforced to be in text format, it doesn't require to be a pr0 to read them. In fact, simple parser
can be done just for practice, without deep knowledge about chosen language. Displaying given object graphic isn't much of a problem too (many .frm loaders around,
(including this one ;p)), so all you has to do is stick to the current format.
Biggest challenges in creating new mapper would be - imho - creating
more user-friendly GUI, probably sorting objects in right order (last one is wild guess, someone more experienced should correct me if needed - i didn't messed with .fomap files for more advanced stuff than reading them, so... :>) and make it working with scripts. First two can be done even now, last thing can wait until you/someone make at least half-usuable application. If stuff will be good enough, i guess it would be much easier to get support from cvet
Due to compatibility reasons, i would recommend C++ here - should be easier for everyone if program find its way into standard SDK tools.
(but if someone make it perl+gtk, i'll give my whole "+1" limit for given month ;p)