Irrandiance volume looks okay from the screen shots, but i’d still suggest having the inner box of the volume closer or over the wall (the outer box acts like a blend based on distance). As long as the individual points of the grid don’t intersect with things and the area covers all that it needs to it’s fine. Irradiance volumes with a lot of resolution can also unintuitively appear more splochy and block than lower resolution ones.
The mirror needs a reflection plane at it’s location.
Eevee currently can’t cast shadows from a HDRi, so it’s better to only use lights for the scene. Otherwise things can be unnaturally bright when they should be in shadow.
For the artifacts on glass you need to set “edge fading” under screen space reflections to 0 and to help avoid screen space techniques to not fail at the edges, turn on overscan under film (both in render properties tab).
I’m not sure what’s the intended look for glass is. Frosted?
There’s a lot of good info on the first posts links for eevee arch viz: