Lots of hot air balloons
I wanted to do this project as a gift, and so I did it a few times for practice. I felt a little bit called out after watching/painting through the class the first time for the "good idea to watch the whole class first," but it was okay, since it was intented to just be a test painting, and I wouldn't have had the attention span otherwise.
Here is my first try:

Second try, I tried to only focus on the sky. Sadly, the sky got worse:

I talked with my friend who wanted the gift, and we agree that sticking to the blue/purple hills definitely makes for a more harmonious composition, but we still both wanted some green. I think it is just a bias about how things "should be."
Third try, I added two more balloons and some birds. Again these additions definitely didn't make things more harmonious, but I still liked it. Also the glitter gelly pen on the ballons is fine because the painting is intended to hang in a baby's room (and my friend and I love glitter):

I also tried this third one on 100 % watercolor paper, and it was so, so much easier to get the sky colors to blend.
Fourth try, I went and did a different hot air balloon class. Which was also really, really good. But I came back to this class for this final painting:

Still absolutely not perfect, but I like it.
I also liked the reflection questions in the end:
About happy accidents: At one point, I almost got the biggest ballon to look like it was rainbow colored by accident.
The last painting was also on 100 % cotton paper. And it was definitely easier to blend the colors. But thanks to the paper, I could also just keep working on them, for better or worse. For worse in that that was how the big balloon lost its rainbow colors.
Weirdly, the masking fluid peeled more on both of the 100 % cotton paper compared to the first paper I used. Which was watercolor paper, but did not specify the composition, so almost certainly not cotton. I patched it up as best as I could.
I don't think I ended up with a proper "main character"/focus in the form of the biggest balloon. I liked the two green ones best. But there's glitter, so it's almost okay.
I liked the reflection on whether the painting has a "consistent light-story" for the gradients and the light/shadows. That is such a pretty way to put it. I'll take that with me in future paintings.
I have my gift, and I learned new things. It was great.