Hey, Halfling!
Could I modify the start biome and biome support segments of the halfling entity to be grassland/hill oriented, rather than any land? Thematically, it makes more sense for them to settle primarily in those areas, and players can still embark wherever they want.
Go ahead. "Any land" was intended to assure that they are always playable no matter what you do to the world and no matter how many weird races you add, as they were an intended "testing"/"vanilla" race as specified by the rules (one to be used to check whether the world is still habitable to regular humanoids)... But I suppose that will work too, rarely do you not have a more suitable place for a halfling to live than a glacier especially as we're not (yet) including worldgen parameters as part of this project anyway, and they're not choking on other civs yet either.
Oh yeah, on your debate about how to develop the world... first of all I think it's a pretty good discussion. The long-term solution to the problem of excessive deadliness would of course be creating lots of non-deadly animals. But if you feel it's urgent (I'm not sure, as we're not hearing that many stories of water strider related slaughter as player reports, but maybe that's because they quit playing after being slaughtered
), then you could try persuading StL to nerf the original bugs a bit to create some less deadly species instantly. I personally have no strong opinion here, I consider it work in progress that could roll either way.
On the other hand creating lots of mammals for example could be done as easily as adding a few bodyglosses to copies of my HOUND. Or - add less deadly versions of things that you want to see nerfed. That's completely legit... by some standard. So for example if the toxicity of water striders is bugging you, add "poisonless water strider" copy creature that is more common and reduce frequency of original as you are allowed to. But that's one way to also make it so much more industrial and less lovingly hand-crafted.