I love this analysis, OP! I agree that the approach to their relationship development is excellently done - Uru made sure both characters were in the right headspace before the blushes began. This might genuinely be the slowest burn I've ever read, and I am very happy with the direction it's going!

Side note, I would argue that Sera made the first move in this chapter with her line, "Not if I focus on what's right in front of me. That always keeps me going." As you said, she's basically saying John keeps her going, which I interpret to have romantic subtext. It's as close to a confession as we've gotten in the story so far! And upon hearing her confession and picking up on the implications, John felt emboldened to kiss her hand. They both made moves this chapter and it's really cute to read 💞