So, I disagree with this.
It was established in 2005 that their masks were forged in shapes to honor past heroes. This wasn’t done simply for flavoring, but rather (I assume) was done to explain why Norik wears a noble-shaped Kanohi, as that’s what the set designers gave him. Whether it is a stupid reason/solution, that is irrelevant, it is the canon and well-established solution to the problem, and undermining it would leave us at square one: Why does Norik have one in a different shape but not the others? Norik cannot be the exception, he needs to be the rule.
Iruini doesn’t break this rule, he is simply honoring someone who wore a Kualsi as well. Now of course, you may ask, doesn’t this mean the other Hagah could do the same, it wouldn’t undermine anything, right? It would. For one, think of how many mask powers, known and unknown, that there are, and multiply that by at least two (for Greats and Nobles). There’s a one in (that number) chance that the mask of the being they’re honoring would wear a Great version of their same mask. That is very unlikely. For Iruini, this is fine, but for multiple Hagah, I’d simply put it like this: One’s a coincidence, two’s a trend.
Now you may ask, “couldn’t they just choose ones that have matching masks?” and this is where it really starts to undermine things. If you’re choosing to honor these heroes because of what masks they wore, then you’re not honoring them for their heroics. Additionally, it does not seem particularily much like “honoring” them if you’re set on sticking with the same shape you already had, instead you are running away from “changing yourself” in their honor.
As for the Felnas/Shelek–But this would not have been relevant when the masks were forged, and it only became relevant when they became Rahaga, at which point they no longer had the masks. (And effectively the entire time since becoming Hagah once more, they’ve been in constant wars, no time to worry about your mask shape, especially to replace it with a mask power you don’t know how to use as effectively as your own.)