@tapio
I've not implemented priorities with any consistency, certainly not different priorities for items according to the active style. I don't want to increase the size of the theme excessively and need to think about whether there are certain key items I should prioritise for different styles. I'm not sure if MF v5, which allows variables in themes, might help.
Forests are intentionally lighter (paler, whiter) than before to give better contrast to paths and tracks through them. As far as I can see, the transitions as you change zoom on MF v4+ are entirely due to Locus's attempt to implement a fade between zooms. With a MF v3 map and the equivalent theme, the fade happens without this effect.