It seems the extrusion multiplier is not linked to the material. It would be better it if was as I often have to tweak this for different filaments. Even just different colours of the same type (PLA for instance). However because I can't record this as part of the material I have to duplicate all my settings. So tweaks to my profiles have to be done multiple times. Failing this a notes section would be a nice feature to have that way I could record information like this.
You can do this pretty easily right now by just exporting the FFF profile and then adding the extrusion multiplier setting to each of your material options. There's lots of threads on the forum about it.