Seems best way to trad these windows then no problems
Then your back to a ladder which defeats the purpose of WFP, either put a damp microfiber over the brush and rub it
above the vent or I use a Fixi clamp on a Harris pole with a damp microfiber wrapped around a sponge. I give them all a
quick rub above the vents every second clean, this keep the whole frame looking spotless without the risk of leaking vents
or water running between the openers.
Just don't put water above the vent and you wont have any problems.