Nifty use of the Cave generator and changing the motif !
Would be nice to get something more rectangular though. This would make it easier to put on virtual tabletop with no scrolling or less dead space if color printing it out,as it easier to work out the size of sheet needed.....
As far as terrain types, rolling hill, possible farm, fields etc, occasional stream (hexside) or river (whole hex or 2 width) etc etc. Maybe tying it into terrain that can be generated from picking a Perilous Shores hex (like you can do for villages/towns). Walls/Fences and possibly some frou-frou like a stray cow etc (not essential but always adds a little spice- can remember adding a cow to a skirmish map on tabletop and the whole thing revolved around stealing the damn thing and keeping the other side from killing it.....)
For grids it would be good to allow for modifying its stroke width, color, and possible center dot stroke width, color (used for measuring esp with hexes) for Line of Sight purposes. The beauty is that this also is in the same motif as the other generators and blends in with other things generated....
Not knowing anything about Haxe and Open FL, not sure what is possible (or advisable- I'm an old-school retired programmer and out of practice and touch- messing with Java and Android but just messing with it) but from what you have done so far, I think it would add another epic tool to this already great set :D