As someone who works on another language that is relatively reluctant to add language features (Java) we regularly face such dilemmas. A user shows up with a problem that could be helped by the language. The problem is real and a language feature would work, but there are many such problems, and adding features to solve all of them will make the language much bigger, overall causing greater harm (even those who don't themselves use the feature need to learn it to be able to read code). What we try to ascertain is how big of a problem it is, how many programs or lines of code it affects, and is there possibly a single feature that could solve multiple problems at once.
So I would ask you this: what portion of your program suffers from a lack of user-defined infix operators and how big of a problem is it overall? Even if it turns out that the problem is worth fixing in the language, it often makes sense to wait some years and then prioritise the various problems that have been reported. Zig's simplicity and its no-overload (not just operator overloads!) single-dispatch is among its greatest features, and meant to be one of its greatest draws.