Yes, you have right, the value 7.5 (without unit, implicit t unit) would be a correct value as is the value 7.5 t (explicit unit t with space separator) too. But previous value was 7.5t (explicit unit t, **without space separator**), which is a mistake regardless of street signs or what iD editor does (may be a bug if suggests different format). The consumer route planner softwares for working properly requires the format documented in the wiki, see https://wiki.openstreetmap.org/wiki/Map_features/Units#Common_mistakes, I intended to fix only those. So please check again the diff about what I changed and verify the wiki. If Romania requires custom format anyway, feel free to document in the wiki (also worth to read the the wiki about maxweight key first) and bring that page to my attention.