When I read elsewhere that you planned to use the drill bit method, I rather expected you would have idle issues, unless you were very lucky.
I’ve posted in the past about a simpler method with the carbs off the bike. You back way off the idle knob and put a light at one end and lower a slide with the adjuster til the light into longer passes at the other end. You then designate that carb as the master and don’t adjust again in the future. You adjust the other three carbs to match slide position of your assigned master carb When ever you do any kind of carb sync.
The problem you have now is that all the adjusters are skewed so the slides are unable to reach the “floor” of their travel and the idle knob can’t control minimum slide opening.