I've finally found the time to get "mostly" caught up with Sumeru content, with particular emphasis on the desert region. I'm impressed with the design of the underground portions and the puzzles have a nice mix of difficulties. However, this continues to highlight the issue with the game's map system (yes, I've already complained about this before). Between the two regions of Sumeru, there's at least 15- 20% that are not shown using the in-game map system. I appreciate the Reddit users who are mapping these caves, but we shouldn't need to do this; proper design shouldn't require consulting Reddit for maps in the middle of a game.
Not having cave maps for "Green" Sumeru was sub-optimal, but at least the caves were mostly linear and not too complex in design. The desert "cave + ruins" underground system is much more complex with branching paths, unlockable shortcuts, and multiple levels. I feel like I need to complete most of the exploration of these areas now while it's fresh in my mind rather than trying to remember down the road. I don't want to write out complex notes for each map marker I place - "Come back to open a door when you have the right permission level on the slate. It's in a room mid-way(?) down the main pyramid in a room full of faux-Egyptian stuff". This isn't all that helpful
Anyway, MiHoYo's environment and level design have both made a significant improvements in Sumeru, so hopefully the map system eventually gets an upgrade to match them.