Changing the tracker to a tracker with the tracker field set to read-only won't work
When a tracker has the tracker field set to read-only in the workflow permissions, it is not possible to change to that tracker. When in the issue edit form the tracker field is changed to the tracker with the tracker field set to read-only, the form is reloaded but without the tracker field (as it is read-only). Submitting this form doesn't include the tracker, thus the tracker is not changed.
Additionally, when the issue edit form is reloaded again, for example for a status change, the form is reloaded to the original tracker and changes in fields active in the target tracker but not active in the original tracker will be lost.