If I consider the current situation, I would say you should build her. She's a 4-star character, and you may likely get her constellations on future banners. Most of the time, 4-star characters are amazing supports, and Collei's constellations are additional optimizations to her overall kit. I'd highly recommend you build her for future use because she's a good Dendro support character in some situations. For example, it's good with Collei to pair her up with either Dendro Traveler or Tighnari to benefit from the Dendro resonance or have her apply Dendro off the field.