I already know that the treasure item from the landscape is not affected by the drop rate, but...
Do the paints for the landscape are affected? Will I get more sycraia paints in arsha?

As I understand it, paint drops from monster zones are effected by item drop rate. However, since Sycraia Upper is the only spot that drops Sycraia paint currently, and Sycraia Upper is not affected by item drop rate, you will not get more Sycraia Upper paint on arsha.

However, Global Labs has announced an update to convert Sycraia Upper paint into Sycraia paint, and have the paint drop in Sycraia Abyssal as well, so (after the update) you will be able to increase your chances of getting Sycraia paint in Sycraia Abyssal by grinding on Arsha, as that spot in affected by item drop rate.

thanks!