Fake it before you make it

I'm currently doing handstand reverse leglift against a wall, I find the headstand version too easy. However I can only do about one rep with straight legs, is it ok to do repetitions with slightly bent legs until I get the strength to do all reps with straight leg or is there any dangers or disadvantages?

Are you doing them in a pike or straddle? Try doing them with a straddle and see if you can get into the 3-5 rep range.

Practicing with bad forms makes you perform with bad form

That is why the next progressions are doing weighted Headstand Leg lift raises and then doing bent arm handstand leg lift raises.

For awhile I was practising negative HS LL against the wall.

Just to note, it is next to pointless to attempt HSLL against the wall with bent arms if you don't have some bent arm strength like dips and are able to do headstand to handstand pushups against the wall. One of the gals tried the other day and it was pretty much a flop.