FWIW, Tinderbox’s XML format is documented here (such as is known). Although you can read from write to a TBX file’s XML as with any other XML, I’m not sure the app is designed for an assumption an external app may be altering a live (i.e. open in Tinderbox) TBX file.
I’d suggest emailing support (info@eastgate.com) if considering such deep level integration.