Thank you for listing the web page for the plugin.
As per that web page you are using version 0.9.3-pre3?
You realize that this project hasn't had an update in over 6 years. Yet reading that web page it seems that different versions of xchat presented different problems with obsidian. I would expect that as xchat releases new versions then they would present new problems for obsidian. Yet, as the obsidian project appears to be abandoned any new problems would be left unresolved.
This may create an opportunity for you to get involved in open source development.
Perhaps you can dig into the guts of xchat and obsidian and resolve the problems.