Here a quick review of what could be improved or fixed:
Content
The "hidden" folder isn't necessary in the zip-file.
Theme
What about marking the theme even deeper into the map? I'll take the japanese castle as example again, as it shows off some nice details which could also be made in Sauerbraten.
Some more screenshot of the map are available just right under this line of text (seems it can't be posted as a link, just copy-past into your webbrowser).
http://quakelive.wikispaces.com/Arena+-+Japanese+Castles
Texturing
- Viruz commented already about the texture-blending-part...
- Nice to see you've putted skytexture on some sides outside the map, but you have forgotten 1 line of mountains at both sides of the map.
- Well, because I made a typo in my first comment, I'll fix that in this one. I still would advice you to use textures which are really from 1 texture-set, as the "gibbie" textures are looking odd against Cube 1's diffuse textures.
- The roof-textures, looks pretty odd to me (as the "2_256_red_thin02" is commonly used as a trimming-texture).
Well, it's probably just a matter of taste on that part =P.
Geometry
- The "Japanese triumph arcs" on both sides of the map, contain some geometry mistakes (compared to those in the zen-garden).
- The roof at both sides of the bright is containing geometry mistakes compared to the rest of the bridge.
- Be sure to hunt around the map for geometry mistakes, as they can change the look of a map and often decrease the world-triangles a bit (which wouldn't be bad for this map, still 160k+ of wtr).
- What about replacing the arrowheads" on those roofs for a more cheaper design? People wouldn't see them from close anyways, so that shouldn't be the issue. I think if you would replace it for "just a steep pyramid on a stick" would do the job just as well.
- The rock just outside of the upper zen-gardens seems to be very unnecessary detailed, as it still looks very blocky. When making things like rocks/mountains/hills/etc, try to keep the gridsize just 1 smaller as the default gridsize at least. Any bigger gridsize is only providing profit (of course don't take a too big gridsize, find yourself a balance. I often use 2 or 1 gridsize bigger as default)...
- Take a look on the mountains, as they still contain a lot of geometry mistakes.
Lighting
- The lighting seems overall ok, but there are many lights which are emitting a HUGE amount of light compared what they actually are. The lanterns at the zen-garden are a very good example of that, you barely see any of the light which the torches are emitting.
- Be sure to check if light-entities aren't over-multiplying each other (like which happens in the zen-garden).
Detailing
- What about adding details like a samurai sword on the walls inside buildings and such? Be sure just to Google some old Japanese habits and implement them into the map if possible.
Clipping/Noclipping
- You did some nice work here, good job! Really nice to see that.
Flow
- The jumppad to the balcony should be set more vertical, if you run into the jumppad and are aiming to the balcony, you'll have a nasty face plant just right above the doorway. Keep in mind, players will be running already when they enter the jumppad, so they won't just stop pressing the forward-button to land gently.
Gameplay
- Be sure to add GA too, as people shouldn't go fight for the YA and Quad only (as it would kill the intention of being a capture the flag map).
- I don't know how much experience you have in placing pickups and creating a good gameplay, but be sure to add more grenades and less bullets, as there are only 12 grenade-respawnpoints, while there are 36 bullets (!) spawning on the map.
- Putting 4 grenades pretty close to each other isn't a very good idea, as it provides spamming the grenades. Be sure to spread them out some more, instead just 2 on each side of the zen-garden (which isn't a bad place for grenades though).
- The number of playerstarts aren't equal and the map isn't containing a playerstart which has been set only for Deathmatch, Capture or Hold. So 1 base has 1 more spawn?
- Be sure to use "entselsnap" for positioning the flags, as they are placed pretty random now (it's binded on "6" as shortkey in edit-mode).
Overall
- You did a fair job just so far on improving the map. Waiting to see even more improvements ^^!