After seeing the formula for Lunar Charged, I went and did some calcs to see the effect of EM and CRIT on the overall damage. This just takes into account one character, but the increase is the same with more, as you would just divide the DMG by 2, 12 etc.

There are two graphs, and they show the increase in reaction DMG compared to the earlier step (so the number you see at x=200EM is the %DMG increase from 100 to 200 EM for that particular CV).

They are almost superimposable, as 100 EM is roughly 34 CV (actually a bit less, 33.26 to be exact, so keep it in mind), so to use them just place yourself in the correct spot and move from there.

As an example, what would be the better investment choice if I had 300 EM and 202 CV? I see that from 202 CV to 236 CV there is a 29,09% DMG increase at 300 EM, and that from 300 EM to 400 EM there is a 25,41% DMG increase at 202 CV, so building CRIT would be more beneficial.

Also, when it comes to reaction DMG numbers, I got a 27,5k with 1,5k EM and 440 CV, while it hovers at around a third of that in most reasonable cases (around 9k DMG for a carry with 300 EM and 300 CV).

This is the first time I do these kinds of TC, so if something feels off please tell me and I will check.

TL;DR EM is a major damage increase early on, but CRIT gets better the more you build. You can expect around 15k to 20k total damage per reaction tick on an average to high investment team.

https://www.reddit.com/r/Genshin_Impact_Leaks/comments/1lf9x8t/lunar_charged_damage_scaling_on_em_and_crit_with/