@Tendo You do a strange combination of looking at high level statistics, picking out bits of data that suit your narrative, then make bold extrapolations. All in a big, difficult to read muddle.
Yes, he didn't finish very high in KOTD4, but he was a finalist in KOTD3.
And yes, Hera can...
Seen high level nomad play recently?
That said, I don't think much, if any change needs to be made to castles, but your statement about castle drops being rare at high level isn't particularly accurate.
You can't balance just based on just cost, the game is not that simple.
For example, if castles were considered OP and their cost was increased as a response, then that would either mean that the number of stone tiles on all maps would have to be increased, or the stone per tile would have to...
Just make them slower to build. I think 1.5x is good, with Sicilians bonus nerfed to 33%.
This way Sicilians' bonus is to build castles at current rate, and other castles are slower and can be denied more easily with towers, which will stop OP forward castles on certain maps like nomad.
So much doom and gloom. If the civs are generic, everyone's bored. If they're OP, there's pay to win jokes. I mean people are even lamenting the loss of Indians elephant archers 11111
These all look unique, interesting, could really shake up mera on hybrid maps, could have some new closed map...
I don't want to nerf their late game. I think they're fine. I'm saying maybe they should be buffed a little early game to balance them a bit.
I just hate the instant unit mechanic, including the revolution
I generally think civs that are good late game need to have a slower start. It's a bit simplistic, but Sicilians' reduction of bonus damage makes them tricky to deal with late game, so people should be able / allowed to get on top of them early with good play.
Only reason I can think that...
Remove magic sergeant spam from Sicilians and give them the Chinese team bonus; that would further cement their long lasting farms and be a little early eco bonus.
Bohemians should lose free stone mining upgrades, otherwise they're totally fine. Give that to another civ with a bad win rate