Heavy class fighter with larger engines vs medium class fighter with smaller engines would be the first issue.
That's not correct, since the MMRCA requirements, are based on the initial MRCA tender, where the Mirage 2000-5 was part of the tender. IAFs basic requirements of a multi role capable fighter still remains the same till today in the SE MMRCA, what changes are limitations or additions depending on which fighters will compete. The MRCA had a MTOW limit of 20t, which just included the Mig 29, but no other twin engine fighter. The MMRCA had a limit of 30t and added AESA as a prime requirement, to have a level playing field with future potential in mind. The SE now, for the first time is limited by engine numbers and not MTOW.
True, but current Air Chief Dhanoa repeatedly stated that IAF is adding 2 squads of MKI, that are on order and in production, while he just stated in October, that SE MMRCAs have priority.