It seems that the ON TEXT event strips out the servername from $rawmsg and $rawbyte, while other events/raws are able to get the full raw message.
I'm making a znc bouncer compatibility script, and znc stores information in the server name when sending the old buffer log. example from /debug:
<- @time=2014-06-25T16:02:24.782Z :Nick!Ident@Host PRIVMSG #chan :testing
When you access $rawmsg and $rawbyte within the on text remote event, those identifiers only return the text from :Nick!Ident@host onward.
To my knowledge there's no other way to receive the source server from these events, other than having to do annoying stuff with /debug parsing.
raw *:*: echo -sg $rawmsg
; ^ has the server name
on *:TEXT:*:#:echo -sg $rawmsg
; ^ does not have the server name