There is no BfA data in Carbonite.Gathermate2_Data, ill update it when Gathermate2_Data will be updated.
Alpha version has all types of BfA mining and herb nodes added. It should record your collecting nodes.
For now u can use
https://wow.curseforge.com/projects/wowgatheringnodes to import notes from
WoWGatheringNodes addon, as they say they got BfA nodes. I didnt tested this solution yet.