I am trying to reproduce this, but for me, at least when the section in which the input is present is open, setting the focus works. Are you saying that if the section that contains the control isn't open, you'd like the accordion to open it before setting the focus?
Also, I'd recommend against using that control, as it has been deprecated for a long time (sine 4.5), and thus isn't maintained, or used by Form Builder or Form Runner. Would you be able to use tabs instead? The fr:tabbable is the way to, as it is used by Form Builder and improved with time (e.g. we're now adding vertical tabs).
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