I think this is potentially unfixable, though it has been mitigated in desktop cases by the icon position changes that came after this report.
Essentially, Froala does the alignment for the more toolbar as part of the refresh process. But the BB code editor works like the code view and thus disables the buttons, so part of this alse involves disabling much of the refresh behavior, so the alignment code never gets called the first time. This is why, once the offset has been calculated once, it will appear to work.
But given that this isn't a particularly significant issue (and isn't likely to be noticable on bigger screens where the icon alignment is more noticable), I don't think we're going to change anything here.