I already replied you through email so there isn’t any need to open the same topic here
You issue comes that you are setting up an achievement with a requirement based on the “Like a post” event (and event that just will be triggered by the user that performs the like)
And what you need is setup a new achievement with a requirement based on the “Get a like a post” in order to make an achievement to users that receive a like
I am sorry but I have set the “Get a like on a post” event, I showed you a screenshot but the event does not get triggered. Really sorry for the inconvenience.
After perform some test we found the issue and we just released an update fixing it, so simply you need to update the wpForo integration to get the issue fixed