change specific string within a message

perhaps the is an easier way, but I am no regexpr sprinf expert

There are lots of possible ways to do this depending on how flexible you need to be. Two examples here include a very simple one if your new parameter doesn't vary much, and a more complex one where the parameter could be replaced with anything required:

By the way, sprintf is not necessarily the best means of performing text substitution as such - it is more for string formatting based on a wide range of formatting options. True, a sprintf formatting command can contain wildcards into which values can be inserted but not by replacement of delineated message elements, only by substitution of defined wildcards. However, it can be used as a reasonable replacement for combine in this case, thus:

If regex then without complications.

I find it interesting how unprecise many questions get asked here, the simplest answer could have been if /p1/ear_r:tz then /p2/ear_r:tz

that would replace it , or ?