Unfortunately I don't own a Pb.HUB or these sensors myself... Hence my reluctance of adding support in the firmware as I have no means of testing it myself. I'm truly sorry if this came across as being indifferent to your questions. We are happy to help out all openHASP users from beginners to developers!
They're pretty cheap, I'd be happy to purchase a few for you if that would be useful? You're Dutch as well, right? Send me a PM here or on github if interested. I'd understand if you wouldn't want to get distracted from the main focus of your project though.
Personally I wouldn't mind the MQTT only route as that's essentially how I'd be using them, however it would be nicer if it was built in.
I was going to post here to report on the issue having been found, but nice to see it already was :-). It seems to work for me with true/false or 1/0, working, so can't extensively test.