Oh, I see the vertical separators now. Maybe a 1 or 2 pixel padding would make it easier to see?

I feel like either vertical space or horizontal separators between rows, would better signal that you're supposed to read left-right, then up-down. With the current layout, my eyes are drawn downwards first and see Floors 10 ➡️ 9 ➡️ 8 ➡️ 6. Horizontal separators, for example, would break that flow and tell me to look right and see Floor 7.

Perhaps adding separators as visual cues to help readability?

9
X X X
--------
8
X X X X
--------
7        6
X X X    X X X
X
--------
...

I'm not familiar with Sandbox Dungeon, but if it isn't being developed by Evan, shouldn't you ask the Sandbox dev to optimize it?

That would make Transmutation an interesting way to roll for high-energy upgraded Trinkets, which I suppose isn't too OP, since you're not guaranteed to have Transmutation.