First of all, thank you for taking the time for such a detailed feedback!
It is true that our updates notes are rather scarce in details – most of the latest changes are structural (in preparation for massive content updates) and we feel would be irrelevant to share.
For the same reason, many known issues remain at the bottom of our queue, but we’ll get there on future updates. Oh, and for the experience rate: any changes perceived are a consequence of modifications in SP campaign difficulty. We’ve been doing some tuning to find the difficulty sweet spot, and naturally easier enemies provide the least XP. The enemy level/XP gain relationship has remained constant for several months now.