Slitherine

Archduke Charles Legion
Would would rate them like Jagers?

Freiwilliger Battalions
what would you rate them as?

EK Legion should be Light Infantry, drilled, conscript, 0-6 bases. Some battalions were 1000+ strong and were intended to be allocated on a 2 battalion basis to II, III & IV Corps. Some battalions were packed out with Landwehr volunteers, so option of poor might be justified. 1st EKL possibly mixed rifle/musket armed like the Jaeger. Others unclear - so musket safer option.

The 3 Moravian Volunteer units are in the same mold as the EKL, just different region. So I'd go the same route - LI, drilled, conscript, 0-4 bases. Inner Austrian version never really got going IRRC

my 2p worth.

I could give you chapter and verse on these units - having done a lot of research on them. However, given the abuse you and your chums handed out, I won't - maybe you children will learn some day?

EK Legion should be Light Infantry, drilled, conscript

Just to point out there is no drilled conscript in the game, you can either be drilled or conscript but not both. Average drilled or poor drilled might be what you were thinking. Average conscript or if you really dislike them poor conscript is the worst troop type in the game.
Pending on how you feel the unit acted you might want to go poor drilled, average shooting but not so keen on going into melee, have to re roll 6's for combat and also cohesion tests and CMT's. But still get two dice for the tests.
Conscripts re roll 6's for shooting, get 1 die for tests unless they have rear support or are defending an obstacle when they will get an extra die for cohesion tests.

Depends on what your take is on them as a unit.