Comment 2 for bug 1467252

On further testing, it looks like the problem here is that the switchbox's width is hard-coded to the English language labels "On" and "Off". Having a label that is significantly shorter *or* longer than this, will cause display problems. So, it works for the "Yes" and "No" switches (which you see on the "Add users by CSV" screen) but it doesn't work for "True" and "False" (which is supported by the switchbox element but not currently used in core)

The French langpack has cleverly worked around this for on/off by setting them to "❙" (that's some kind of unicode pipe character which is wider than the ASCII "|") and "O" (capital-O).

For "Yes" & "No" it has "Oui" and "Non", and as a result it has display problems.