I do not not if believing, however, that they will bring there also additional militants. If they had those they would jot have needed to move a considerable quantity of sirian (and not) terrorists from northern Syria to Libya to continue the fight against Haftar.
Turkey is involved in at least two fronts now, and it is not clear if they have many more "moderate terrorists" to spare for additional operations. They could move them from the traditional kurdish areas to Idlib, but then they could face problems there.
Or they would have to send turkish army personnel, and not in observer/patrol duty, but in that case it would be more difficult to justify it as not an invasion, and the loss of considerable amount of turkish army soldiers could also cause internal protests and spell the end for Erdogan.
What Russia is doing is trying to get its objectives, without starting a hot war against everyone that has different goals.
I am not even sure that not having the ceasefire work in Lybia is a problem for Russia. Haftar is also not the most trustworthy individual, and if the ceasefire had worked, Turkey would have focused more of its concentration on Syria.
This way instead Turkey has to move militants and suppor to Lybia and they will die killed by haftar troops, but limiting Haftar victories for the moment.