I think this may be a “known bug”. We have not used radio buttons in the “simple form” entry mode before, and I believe nobody has tweaked the output form that the Html Form Entry module generates to properly render radio buttons in the “simple mode”.
A couple points, though–is it that   that is really causing the problem? Could you include the whole generated radio set, including the No button?
Also, a workaround is to a select list, which is what we do in these cases… it should work properly, and support keyboard navigation and selection.
In my example, I provided an example with PIH concept mappings (instead of conceptIds or uuids). You don’t have PIH mappings, but are using CIEL mappings (ie. CIEL:5090).
For your example, add the answerSeparator attribute:
@ball I am having this issue with the yes_no style for Boolean options, which is strange since the output is the same as the radio button with an tag between the radio options. Any idea what this spacing is for as it seems to break the radio buttons in this case.