Fireballs dont light up candles

Well Fire Charges do which is what the player would use, this sounds like it might be more of a feature request...

They actually do! It's just that the fireball goes right over it in the setup you used. You'll need to use a downwards-facing dispenser from the top to light it.

I am unable to reproduce this issue in 20w51a. As stated above, a downwards facing dispenser with a fire charge in it, is able to light a candle.