I know that Build 20 isn't even out of the door, but IMHO one major focus for b21 should be on the Encyclopedia. It's a mess and it will be even messier when the mines-worldsavior branch gets merged.
Here, a small incomplete list:
- Production times are wrong or missing.
- Lores and citations are either missing (barbarians) or absent in general (all other tribes). I would vote for getting rid of them entirely.
- Experience Levels are incorrect (Deep Mines) and or missing (Deeper Mines)
- Working Places are incorrect/wrong worded (Master Miners can work in all kinds of mines AFAIK)
These are just some I recall out of my head and I'm pretty sure I'm missing many more. IMHO the Encyclopedia should be as accurate as possible since it is also the entry point for newcomers regarding information about tribes etc...