I haven’t found this to be a problem in practice. You generally can’t grep for the complete message anyway due to inserted arguments. Picking a distinctive formulation from the log message virtually always does the trick. I do take care to not place line breaks in the middle of a semantic unit if possible.

Yes, I find the part of the message that doesn't have interpolated arguments in it. The problem is that the literal part of the string might be broken up across lines.

And to add to this, you rarely need to read a log message when just visually scanning code, its fine going off the screen.