Hi Cyril,
Normally, I would suggest upgrading to 3.3.4 if
possible, but even upgrading does not yield the results you want because
the tooltip is placed at the bottom of the GroupX. Also, Tooltips are
ignored on fields inside a GroupX/FieldX. So this is probably a good
feature request for FieldX and GroupX fields.
I would use a custom template.
regards,
Randy