I like it! The colors of your limited palette complement each other very nicely. The piece has a wonderful feel to it and inspires the imagination. Just enough detail without getting bogged down by it. (I struggle with over-detailing a lot and can't seem to shake it.)
You mentioned "scale" a few times. I find your scale believable enough. However, have a look at this post of mine, it discusses a simple tool to get a handle on proportions. You can use it to transfer suitable items from unrelated reference photos to your phantasy scenes:
https://peakd.com/art/@wulff-media/video-night-hunter-watercolor-painting-and-bonus-painting-hack
About the warping issue:
Heat the tape with a hairdryer before taking it off to prevent damage to your paper.
To get all warping out of the finished piece, buy yourself one of these cheap "frameless" glass frames with those metal clamps and frame your piece under glass for about a week. I do this with all my paintings and hang them right over my desk. As a nice side effect, it forces me to study my mistakes and hopefully not make them in the future. It is amazing how many "I should have"-discoveries came out of this for me so far :-)
Have a wonderful Sunday and happy painting!
Thanks again! It's lots to learn in one go ;)
Balance is very hard for me. I mean details and all. I guess I should keep to the minimum for now. Most of my attempts start good and at some point I overdo them.