Coralgurls tank build 180 - it's ALIVE

[gregzz4]

1/4" over 6 feet isn't much to worry about, but it's a good thing to keep an eye on if it changes again
You could try re-levelling it with the stand feet, but do it in tiny bits and evenly between each foot to avoid scary things happening

No scary stuff yet, but let's think about the future
If it continues to sag to one side, are you able to put a jack post under it on the floor below ?

When we had a freshwater 6' 125g against a load-bearing 6" 2x wall.
Our tank still listed a bit to starboard (by the same as your 1/4"), and a bit aft
It was a bit disconcerting to stand in the middle of the room and be able to create waves by bouncing off our heels while keeping our toes on the floor .....
Our tank spanned most of the joists, but missed the last one

With a room width of over 12 feet, the joists just weren't meant to handle the weight

I thought about a post setup in the recroom but would have needed to build a cabinet where I didn't want one, just to hide the post - about 24" away from the load-bearing wall

I just kept the amount of traffic in our livingroom to a minimum and all was good

As for your sump cracking, it's hard to speculate
Do you think your stand shifted enough to crack the sump glass, but not affect your DT ?
Tough call, but I'd say not. The tank probably would have leaked first as it has larger panes