I had a single xenia sprout that grew into a HUGE colony over about 3 months. Right before I had my death run in the 125g the entire colony literally melted in 2 days and there isnt a trace I ever had xenia.
Not sure I'm gonna put any back in, as it did start to grow ALOT and I hear it can take over a tank.
As far as your mushrooms, they don't like alot of light, do you have them on the floor with some kinda overhang? Mine are growing like crazy under a slight overhang of rocks I placed them under.
I alsohave the same issue in my pico with the shrooms
. I added new lights and now they are tiny. Hoping they will adjust soon.