This post was originally from January 1st of 2020. I was pretty harsh in the original post, so I've gone through and toned down my language as of the 8th of April 2021.

From what I've seen from this map so far, It's a map with a lot of cool concepts, with poor execution. The map runs terribly from what I've seen, at that is most likely due to the spamming of water volumes, when only 1 or 2 would have sufficed. The same goes for Hole volumes. For context. The way hole volumes and water volumes work, is that every single one checks every tic to see if a player is inside of one, if a player enters a hole volume collision for the ground is removed, if a player enters a water volume, water physics are given to the player. Having so many adds quite a lot of strain, Unturned already has a really hard time with optimisation, so adding this extra strain isn't a good idea.

As for the issues you're having, the water issues are caused by how Unturned renders water, especially water volumes, normally these issues would never be encountered on a regular map size, however, Insane maps pushes what the game can render, which is why it was removed from the game in the first place. The railway trench has "wonky physics" due to it using hole volumes.

This map gives me a ton of nostalgia for the early days of Unturned map-making, where people were just starting to pick up the editor, and when compound was just starting to become a widely accepted map-making technique, as no one really knew how to make custom assets at that point. Locations like Krepost Military Base and the mountains around USS Borealis remind me of locations that I wanted to make back when I was just picking up map making. Some locations, like Yastreb International, have some pretty cool ideas, the gravel runways are a nice look, I might experiment with something like that in future projects. The train line running through the middle of the runway, while unrealistic and 100% a safety hazard, is really cool.

Speaking of the mountains around USS Borealis, the boulder work on those mountains doesn't look very good. The boulder work on the majority of the map doesn't look very good. You've taken to flattening boulders and resizing them into balls, and only using said boulders, instead of using some of the more jagged boulders, like 8, 2 and 3. The material use on this map is all over the place as well, "Farm" randomly shows up on mountainsides, riverbanks, and even under said rivers.

Port Lisa having the curved dock is also pretty cool. Imperiya Bridge is also nice, I've wondered why we haven't seen large bridges in Unturned before, and looking at it here it's become somewhat apparent. Unturned doesn't really have a ton of large roads or large cities, a bridge like this looks out of place in a vanilla Unturned setting. The compound on the bridge is actually fairly good, so props for that.

The pipelines around the map render out super quick due to how object LODs and scaling work, they render out almost immediately if you get even a little bit away. Scaling doesn't resize the object's LOD.

There are a ton of random locations all over the map that just lead into the void, and exist for no apparent reason. There isn't anything inherently wrong with random small locations, but try to consider why they're there.

As for some of the issues people are having, with random holes to the void, and floating objects, it's most likely caused by them not having the required Greece, Hawaii and Canyon assets installed.

Speaking of Canyon assets, I'd avoid using them, as all of the objects lack "Nav" colliders, these colliders are what dictate animal/zombie pathfinding, without them, zombies/animals will just walk through the objects. The Canyon assets were never created with the intent to be used anywhere outside of the map they were made for, which is why they don't have Navmeshes.

You've already stated that you don't want to pick up Blender so you can add custom content, so I won't try to persuade you. As for it causing more problems, it really wouldn't unless you monumentally messed things up, though, for this project, it'd be best to not go around and replace all of the compound imo, you'd want to start fresh if you're using custom content, and you wouldn't want to be creating it for an insane sized map, that would take far to much time for what it's worth.

This map feels like a relic from 2016, and I can appreciate that.