Forums mIRC Help Showing Topic For Active Channel

The RFC1459 is from May 1993 and the RFC2812 is from April 2000, indeed, but that doesn't make them any less relevant today.
'/topic #channel', as defined in the RFCs, returns the topic on any IRCd that remotely conforms to the RFCs including UnrealIRCd, to name the one you had mentioned.
And mIRC doesn't do anything special with the /topic command clientsidedly, it just rawly sends whatever you enter to the server.

Now, it's true that mIRC knows the topic already and that there is no actual need to ask the server for it,
but considering that mIRC outputs the topic (as well as the additional information on who set it and when) properly that way,
and that codeseven had specifically mentioned the universal and easy-to-remember /topic command, he should be told how to use that correctly one instead.