the liquid starlight doesn't actually interact with entities at all besides giving night vision, and that is excusively in their source blocks. is this intended behavior?

Also while not related to the tangibility of liquid starlight, the starlight in the lightwell is still white instead of blue

Starlight is supposed to be white. Optifine has a bug where it makes liquid starlight blue.

It has been intangible like that for an incredibly long time.