The chief advantage of Augusto Boal's term "joker" is that it separates a role -- instigator, initiator, actor, etc. -- from a position: teacher, leader, facilitator. Roles can be rotated and re-distributed across participants. Positions, however, are part of an institution or structure and don't change as fluidly as roles.
When people use the title "facilitator" instead of teacher, as I have often done, it reflects a desire to "de-position" the teacher, to break down the position into the various roles played and redistribute those, so as to democratize the learning process. But, unless the structure or institution is actually altered, "facilitator" just comes to be another word for teacher.
Teacher is a position. In the interests of building a horizontal learning process, the roles that get gathered in the teacher need to be disaggregated and re-distributed. Those that are firmly tied to the position (e.g. giving grades in a school course) need to be clearly identified as such. Just calling yourself a facilitator doesn't help and may serve to mask the difference between roles and position.
For Jacotot, the position of the teacher (literally master) is that of the person who subordinates the will of the learner to her/his own will. This seems utterly undemocratic, but for Jacotot it is in fact a crucial element of emancipatory learning, because while the student's will is subordinated to that of the teacher, their intelligences are equal.
I think the joker role is instructive here. In a game, the joker temporarily subordinates the will of the players to her/his own, and the players accept that role. As Huizinga says, all parties to the game accept the premise, and their own subordination, because the joker's powers, and their subordination, exist only in the world of the game. We know we are equal outside the game and that we don't lose that equality when we play.
Whether the "world of the classroom" (workshop, etc) is democratic is a different question because we may not have equal standing outside the classroom. Nearly all schools are undemocratic as organizations, certainly from the point of view of the student. It is possible to design a school (workshop, etc) in which the teacher is in fact on an equal footing with the students, institutionally.
The learning process -- if it is to be emancipatory -- involves the separation of will from intelligence, the dominance/subordination of wills, and the equality of intelligences.
It is easiest to see this in an organization or context in which the person who is teaching is really on an equal footing with the participants -- who can, if they choose, stop the process and vote to move on, stop, or back up. In that case, which I have experienced several times when teaching for unions, community and left political organizations, the "teacher" or "facilitator" has no position of power or control in the institution. The teacher becomes the joker: the joker's will is dominant within the workshop, but does not amount to political power. (My Carpenter's meeting story, in Popular Education for Union Democracy illustrates this.)