I ran cz servers for about 10 years and
the only way "I" know of is nav editing.
CSGO seems to have fixed this and the bots automaticially crouch when needed but csgo was changed into cs2 and OF COURSE the problems of not crouching is back AGAIN in cs2.
Give nav editing a try.
It seems overwhelming at first but take it a little bit at a time until you get there.
All you are looking to do to solve this is execute a nav_crouch command while looking at the nav area and then save the nav.
What map is this?
I can possible look up
my now what 20 year old!
server to see if I have that map and I would have certainely fixed it and can get it to you.