I'm sorry but I cannot understand any argument that says changing the race of a character within a story fails to respect the core mythos (unless that character's race is a key part of the story and it's conflict - eg Luke Cage)
I read nothing in the IDW MASK books that tried to turn Matt Trakker into a character that suddenly had to deal with issues of homelessness, gang violence, or historic subjugation because he was suddenly African-American.
As far as core concept -
The original Matt Trakker was a father and leader of a leader of road warriors who piloted transforming vehicles.
The IDW Matt Trakker is a son and leader of a leader of road warriors who piloted transforming vehicles.
The IDW Mask series dealt with the conflict between a global arms dealer/terrorist organisation (VENOM) and those who formed to stop it (MASK), who each pilot amazing vehicles that are capable of transforming for multi-terrain combat. It dealt with people ads leader happened to be African American.
There is nothing in the core concept that is related to race and yet this gets targeted by people who want to trash a book because they lack the empathy to be able to identify with a character that no longer looks like them.
I don't remember seeing these issues raised with the Power Rangers reboot, when they changed the race of Trini, Zack, and Billy (but admittedly I don't really follow that fanbase anymore). So clearly race didn't factor into a story about 5 teenagers being provided mystical powers and piloting mechanical beasts against a space witch.
So we're talking about a niche within a niche property. Of which the core concept is vehicles which transform into other vehicles.
I doubt that race is factoring into poor reception any more than a lack of being able to target what MASK should stand for in a modern world, and therefore creating a touchstone for wide recognition beyond that niche market. Similar to how GI Joe ARAH struggles to define how characters largely characterised by old-school warfare are supposed to relate to a modern world.
I can't quite tell what you're trying to say here. On one hand you're condemning IDW for making nuanced changes to character's previously stated bios and backgrounds and then praise Marvel for marking nuanced changes to character's previously stated bios and backgrounds.