...
Actually it is so complicated that I have to look it up and the answer is not that simple because the weapon are different in so many ways. But you are pretty close.
As far as I know only Luch uses the point blank mechanism but Centaur is using better modifier vs cover.
Lets check modifier first using 222 as base line:
222
Light cover accuracy 0.5, Light cover damage 1
Heavy cover accuracy 0.5, Heavy cover damage 0.5
Garrison accuracy 0.4, Garrison damage 0.25
Ostwind
Light cover accuracy 0.5, Light cover damage 1
Heavy cover accuracy 0.5, Heavy cover damage 0.5
Garrison accuracy 0.4, Garrison damage 0.25
Luch
Light cover accuracy 0.5, Light cover damage 1
Heavy cover accuracy 0.5, Heavy cover damage 0.25 (x50%)
Garrison accuracy 0.5 (x125%), Garrison damage 0.3 (x120%)
Centaur
Light cover accuracy 1 (x200%), Light cover damage 1
Heavy cover accuracy 0.5, Heavy cover damage 1 (x200%)
Garrison accuracy 0.5 (x125%), Garrison damage 0.35 (x140%)