Avi K: The Star-K states that R’ Eliyashiv held that one makes a Mezonos on cooked rice and rice cakes. To my knowledge no one is machmir as you state in your last sentence.
LB: When it comes to questions about brochos you should ask your LOR and follow his opinion. This way you have no doubt. As for your example about the mezuzah, yes the Ashkenazim, based on the decision of the TUR, comprmise between Rashi who holds that it should be “vertical” and Rabbeinu Tam who says it should be “horizontal”, compromise and place it slanted.