For example "aa" has a clearly non-abbreviated eraAbbr string (and empty eraNames)
<era type="0" draft="unconfirmed">Yaasuusuk Duma</era>
<era type="1" draft="unconfirmed">Yaasuusuk Wadir</era>
If possible, it'd be nice if these were moved to eraNames & eraAbbr created for these languages.
I don't know if there's any validation tools, but some sort of check to make sure that the abbreviated strings are < 6? characters or spitting out a warning might be nice.
It's also unclear to me if the abbreviated era is appropriate for use in a "short" date format (eg: 4/4/2014 AD). Some of the forms seem rather long for that (ni J.-C.)
Given that the "narrow" form is shorter than typically used when writing out dates, I would probably prefer that the guidance for the eraAbbr field be that it should be < 5 characters.