As the only 2 civs with the cav archer , russian & otto cav archers have little differentiating them except a few things
Russia - +20% HP & 10% atk (due to the age 1 card and royal guard)
Otto - 100% damage vs vils.
Makes otto cav archer kinda niche.
maybe a change then is to change the irregulars card a bit
something like - 10-20% atk (or maybe just 15% rof decrease) and just negating the 0.5 bonus vs vils (right now it gives net bonus of 1.25)
Thoughts