This initially started as a retrofit / continunation of the original WoW Titan Panel Reagent Tracker addon by L'ombra, maintained so that it functions for WoW Classic / TBC / etc. Over time features have been added and the code base changed enough that it may no longer merge well with the Retail version.
This addon is developed and maintained via this GitHub repo. Please submit issues and requests directly via GitHub. It is mirrored on CurseForge and Wago, so should be accessible via both the CurseForge and WowUp clients. For what it's worth, I recommend the WowUp client.