Indeed, ailments don’t hit, so won’t be affected by this node. However we have started to write these descriptions slightly different on newer skills, so those should be less confusing. They should say “Rive hits deal more damage”, referring to the act of hitting with Rive.
And in some cases those are really old nodes and haven’t been updated.
This does indeed mean that YOU, the character deal more damage while spinning. So so if you have a procced melee ability that triggers while you are spinning, it will deal more damage too. Though we might change this one as it can be a bit confusing.