Hi @JamesSchultz,
Despite what some tool providers would have people believe (I'm a Canvas admin for a public university), the config/XML is not magic. From my experience installing LTI tools, I can tell you that the XML file would be read only once upon installing the tool. From the UI, it's definitely not possible to re-do this process without reinstalling the tool. From the API side, the documentation seems to suggest an XML reconfig might be possible, but i've never gotten to to work myself. If you know exactly what the vendor changed, it's possible to modify the parameters via the API manually (Canvas really just reads the XML file and assigns things to it's own database prescribed). I have a python script to assist with this available at https://github.com/cmcasey79/canvas-scripts-by-chris/blob/main/update_lti_parameters.py (pretty well tested, but I'd always advise attempting things in a test environment first). Again, some vendors might say you have to reinstall their tool or reload the XML, but it's really not necessary if you can just figure out what they changed.
Hope this helps a bit!
-Chris
