When you open text event dialog and scroll down to Channel Half op the text for $1 and $2 appear to be reversed in the description.
$1 seems to be the person giving th e half op and $2 seems to be the person receiving it. Which is also in line with other similar events like operator, voice and the remove counterparts of each status. Of course the default event seems to be setup for the right order of $1 ans $2 its only the description that is misleading.
II am using Xchat 2.8.6 compiled form freebsd ports on June 22nd after a fresh portsnap.
Obvious work around is to ignore the help text for this event. I checked several others channel related events and they seem to be all in line but I did not go over the entire list. If I find any other mistakes I will point them out. This is a very minor bug but I thought I would bring it ot somsone's attention.