I have to work tomorrow morning, so in the interest of not getting this conversation bogged down by people thinking I have a specific plan I want to enact, encouraging Tenshi to audition for a play is good. If we can get her into a Bhavagran play, so much the better, but simply being supportive of the interest at all is good. If plays aren't terribly common in Gensokyo, perhaps we can hook Gensokyo and Tenshi up with a Bhavagran director who can run the show while Tenshi plays the lead.
If that idea sputters in the interest of getting Tenshi in with the rest of the celestials, the other idea I had was to propose Tenshi start running an advanced-level danmaku training class. It gives her a chance to put forth her love of combat in a positive manner, and it gives her a degree of control over her fellow celestials as their teacher. Now, normally there's not a readily obvious need for such a thing, but between Marisa and the SDM invasion, I think it can be sold as something the other celestials could stand to learn.