High elves got 1 unit, high elf warriors, back when the game came out, and now 13 (?) years later they got their second unit.
Rohan is just terrible, thematic heroes you want to play with are nerfed for no reason; Theoden is so overpriced and underpowered he is a joke, Theodred has no fate for no good reason, Gamling, Hama, and Grimbold are the only named captains who do not have 3 might. The two fieldable heroes in Rohan are Eowyn, Erkenbrand, and arguably Grimbold, but that is only because he provides the strenght 4 upgrade to your warriors.
Furhtermore, Rohan cavalry are actually really quite bad, they are lightly armoured, are only fight 3, and have no lances. Sure they all have bows but what with the movement penalty that isn't a very big deal. Their throwing spears are also now worthless thanks to the nerf to moving and shooting.
Warriors of Rohan are also pretty bad, this is because they have no spears, it doesn't matter they are fight 3 and have 5 defence with a shield, if they had spears they could act as cheap infantry to bolster numbers, but without spears they are just a liability. Sure you could ally in spears from another army, but then why not just play another army instead, considering Rohan have nothing going for them.
The only way to make Rohan work is this:
Warbands 1,2 and maybe 3 if you are feeling suicidal:
Grimbold, and then either Erkenbrand or Eowyn
As many helmingas with shields as humanly possible, with a son of eorl here or there (only competitive elite unit Rohan has), and maybe even redshields if you are feeling adventerous.
Other warbands:
The best hero for points from another army (this will kill theme but give you a fighting chance so why not)
spearmen from another army, preferably with higher fight value than 3. Wood elves work because of their low defence, as do arnor because of their high fight.
With the above set up you get a strength 4 frontline being supported by something with a decent fight value, maybe you will kill a few models
Also, because Redshields and Helmingas are key to victory, and both use the same sculpt of foot model, you are required to either split your models into two different paint schemes, or go mad trying to remember which model of sculpt A is a helmingas or a redshield.