Network Label Color limitations
In the servers list, you are given the ability to "name" each connection and the option to use the given name as the label for that connection in place of whatever the network provides.
Example, Undernet's ircd.conf defines the network name as UnderNET. This can be overridden in AdiIRC by using the label as the network name. So you could, for example call it AwesomeNet.
That brings me to to the minor issue I've noticed. You can set colors when renaming that connection. The colors will appear in highlight messages and the monitor windows. It will not, however, appear on the Treebar or the Status bar.
I could be wrong, but this seems like it'd be a quick fix. I included a screencap. Hope it helps.