Yes, a friend completed the Jabiru course and became a restricted L2 (Jabiru). He had to gain experience to get an unrestricted L2 and can now work on any aircraft, any engine (he worked on Rotax engines, under supervision to gain the experience).
The MRC and the HGFA Aircraft and Engine course both get you a L1 (for any type of aircraft). The iRMT Rotax courses held with Bert Floods in Vic, don't get you an L1, but would certainly count for a Rotax engine L2. Any course will help towards a L2. You need to send in a copy of your Certificate together with the paperwork to the Tech Office.
I think the wording in the Technical Manual is that 'other forms of evidence may be considered on a case by case basis, by the Technical Manager'.