I don't mind having civs with positives and negatives, I enjoy that. For me, for the Gaul's, I just don't see their upsides as necessarily stronger than their downsides. I do think they have some strong upsides to them, but I would be good with some targeted bonuses. Like, to me, if you removed the Harbor rule with them (and simply made it "land specialty districts must not be adjacent to the city centre"), that would be a simple, (presumably) easy, and overall small boost that would help them out a little bit. Personally, I think they could also use a further adjacency bonus - given they don't get normal district adjacency bonuses, even a full +1 adjacency per mine would not be totally out of order. Or perhaps you go even further with the positive/negative with them, and remove ALL other bonuses for districts, but convert them totally onto mines. So, for example, remove the campus adjacencies for mountains, jungle, reefs, geotherms, etc..., but give them +1 for each adjacent mine, and then also let Gaul put mines on flatlands, for example, and now you have a civ who has completely turned upside down in how they plan and build. Give all of that, and you create an even more unique civ. Maybe that's too strong, or maybe it's even worse, but they would certainly be even more unique to play in a setup like that.