If your string needs to be presented in multiple locales, you probably want to go a step further and use something like the ICU syntax and a proper parser and formatter rather than rely on manually formatting things yourself. Otherwise, that dynamic data is going to give you headaches when you have to deal with plurals and genders and such.

I’m not sure what you mean by manual formatting. You do need a place in your program where you fill in the parameters into the respective localized string template. I agree that the printf format syntax is somewhat limited for localization [0]. But whatever localization string format you use, you don’t want arbitrary expressions embeddable within it.

[0] though GNU libc does let you extend it: https://sourceware.org/glibc/manual/latest/html_mono/libc.ht...