Hehe… 
Well, I have about 160 knx items, all defined through a knx.things file. This was quite a bit of work, but a lot of copy&paste (and slightly change the labels and GAs, I have a well organized GA table…)
After all channels were defined, I used VSCode “Create Items from Channels” to generate the items. Worked pretty well
So, all in all, I would say Pain level 3 to 4 .