HAVE APP DRAWER CLOSE AUTOMATICALLY
“if I open the launcher by swiping from the left, the watch screen will never go into dim mode until I swipe back to the watch face”

ANSWER:
Whether the app drawer closes automatically or not depends on its content. If you have a clock bubble, it will not close automatically (some people like to use the bubble cloud as a “temporary” watch face replacement when they need the extra information it can display). But if you remove the clock bubble (just change the star to a red-x in the Wear Cloud Editor) → the app drawer will close automatically after 10 seconds of inactivity (that’s when the watch enters ambient mode normally):

1. Open Wear Cloud Editor → https://youtu.be/SgiPxzuHeyc
2. Find “Clock bubble” in the list
3. Tap the symbol on the left twice
↓
(see screenshot)

TRANSPARENT FAVORITE CLOUD
Another case when the app drawer is not closed automatically, if you set the background to transparent, and use the favorites cloud to augment your watchface. I talk about this scenario in this video: https://youtu.be/wv3783-o_Ss