While Guild supports output scalars, that’s really more for folks who don’t want to bother with a specific log library and would rather just scrape/parse their script output. If you’re going to far as to create a callback function for Guild, I would just log whatever you want directly and disable Guild’s output scalar support altogether.
Guild uses native TF event files for its scalar stores. You can log scalars using any number of libraries (e.g. tensorboardX, etc.) Along with that, you can log to any of the other experiment frameworks directly. If I’m understanding your feature suggestion, you’re doing that anyway by way of the callback function. By logging directly, you avoid the complexity of Guild scraping/parsing output and then also calling back into your codebase.
Am I understanding things correctly?