The role of facilitators or mediators can only be successful if there is the political will by the two parties in conflict to arrive at a political solution. The credit for the success must go to the parties in the conflict. Facilitators and mediators can only play a catalytic role in creating a friendly environment in which the two sides can engage in talks. Another reason why a third party may be necessary is that often the parties do not have the infrastructure or the technical preprequisties for a sustained negotiations process. A facilitator can help the two parties in conflict to agree on what issues should be tackled first.
Facilitators can also help set a loose time frame for the talks.
A third party can also be an effective communications channel. Such confidential communications will enable the building of trust between the two sides. There is a lot of nonsense going on about foreign interference. Peace in a country depends on the two warring parties themselves wanting to resolve the conflict. That political intention sets the agenda.