In the game, you can only use the magic level that corresponds to the level of the built guild.
If you have 2 castles and both are below level 5, then to use level 5 magic, you need to build two maximum levels.
2. 2 minutes per turn is completely unacceptable; the minimum should be 4. Since we are playing online, sometimes the connection leaves much to be desired, and the most important thing is "chains" and "splitting" of troops. I can't imagine how to do them on SOD in 2 minutes.
Besides, the Chaos League played on 2 minutes, and they seemed to manage. You just need to think faster.