Thank you. I do vacuum but may need to do a better job and do have live plants. Will be adding more. I do have 1 assassin snail and it seems like he barrows. So I might get more. They are the only snails I like.
I have assassins in my tanks as well. They have gradually eaten most of my other snails down to a very manageable population; the assassins themselves are seen only rarely, often going completely undetected for months at a time. I tend to forget about them completely until I occasionally remove some of the accumulated empty shells of their victims.
If this were my tank I would remove about half of that sand. This can be done by simply siphoning some out every time you do a water change. No need to cause a sudden large disturbance, just gradually remove some each time until you get to the level you like.
I keep Malayan trumpet snails which whilst similar, and also bury to an extent, I find they reproduce just way too freely. Fine for feeding my botia. I think most of your plants I can see would take feed from the water column and just anchor for roots so would agree with half what you have. The good thing is that being able to see the front glass edge you will be able to see any potential problems starting as you will see the glass/sand go black.