I understand the float level is to be set at 22mm, which is what I adjusted to, but fuel levels in the bowls are not the same. I'm wondering if some needle valves not sealing properly, or float buoyancy is different or something. All floats swivel freely. . . . I thought my 22mm measurements were spot on, but maybe I need to re-visit that.
This can be an issue, but first maybe check: the float angs where the tiny valve tip sits get little dimples in them because the brass is so soft. This makes that valve "stick" a little bit, until the bowl fills far enough to force the tip of the valve to roll and snap shut. This results in a too-deep bowl.
The fix for these is: using an equally tiny file, smooth off the tang until the dimple is gone, then polish the tang shiny again with a bit of 400 or 600 grit emery paper (O'Reilly's Auto). Then reset the float height, as this work tends to bend the tang away from you while you work on it!
On the 750K0-K6and F0/1 with non-PD carbs, this is chronic, making dimples much deeper than on the smaller Fours. On these bikes it can cause bowl overflow, often does. The smaller Fours have much more active bowls because the smaller bikes jounce on road bumps more (lighter weight) and help close the bowls valves.