I’ve also think that foragers currently are way underpowered.
Early on, they can provide some food and variety but nowhere near as efficient manpower wise as hunter or fisher.
After only a few years, once you setup your first farms, foragers are basically go to useless status other than collecting herbs and willow, if they exist
Late game you can add medicinals roots, if they exist at all as well.
So their main drawback is they are very situational.
A tier 2 upgrade would be welcomed, however i think there should be a twist added.
Instead of letting them freely grow herbs, how about they would work similarly to hunter lodges and they would need to setup an area where they could grew the herbs/roots.
Depending on the coding complexity i wouldnt mind if they would actually require “seeds” aka the same plant to be replanted, e.g. planting 10 willow but yielding 11, so it wouldnt make completely obsolote the normal collection/trading, but would give some extra.
Or there should a limited area where those herbs/roots could grew, likely at some spots that has high water content (swampy areas or near bodies of water). If the map lacks those there could be an option to have an extra building that is consuming water from the wells and irrigate a small area, making artificially swamps (amount of water consumed would be calculated after each tiles)
p.s.
As mentioned there is a plan for a tech tree so it could be added there in a way.