Khuveshavagan texture missing in lower graphic settings... Quickfix?

Well, I'm lucky enough that my old old laptop can run EB2 but only in bottom low graphic settings. I will probably buy a new one in the next months to be able to enjoy EB2 in all its splendor but for now it'll have to do.

Only problem with playing in lower graphic settings that I've found so far is that the magnificient Kinsmen Cavalry (Khuveshavagan) are missing textures in low and medium (you can see through them, like ghosts in armour) while working ok in high and very high. A quick fix I was planing to use was to assign the higher quality textures also to the lower settings for this unit in particular, I suspect that's a matter of doing tiny change in the txt files or in renaming textures, but, while I knew how to do some changes of that kind in RTW I can't find the way in M2TW, can someone with more experiencing help me with that?