I have no need to. I’ll leave the d1ck-swinging desire to answer every post to others on here. I was just answering the original question in so far as there isn’t a missing part and that slot is just a simple frame drain. If I don’t know something, I’d rather not continually post a load of ‘what-ifs’. As I’ve said before I find it best to answer if I know something and to read, learn and say nothing if I don’t.
As you’ve asked though, anything is possible, but the work involved in being able to adapt that slot into some sort of useful drain channel unless you have the ability to fabricate and the skill and equipment to TIG weld ali aren’t worth the time involved. I’d either use it as it was intended and accept it doesn’t do much and find another way to deal with condensation, or stump up thousands for modern double glazed units.