Got a call from the shop today, the Michelin rep was in town. Nice guy who immediately inspected the cracking pair in front, before proceeding to inspect the non-issue back tyres too when I reached the shop.
After that he asked a few questions on how often I drove, what tyre pressure I am applying, where I normally parked (in shade/under sun). He commented that even with the defects, the tyres will still be usable until the end of life, albeit with more noise, but will still be able to disperse rain water properly in wet conditions.
When I asked if this issue could be a manufacturing defect, he denied it. However he allowed me to claim based on the remaining life of the tyres (initial tread height minus current tread height), which comes up to RM40 per tyre.

. As long as I changed into another set of Michelins
In short I claimed the warranty and changed into XM2s. Yes, still giving Michelin another shot, hope that this set turns out well.