About what you put in the log message: You can also put different fields in a line of text. Not getting the advantage or trade-off here.
About the internationalisations: As non-English developers we force all our systems who have logging internationalisation to English system language so we have a common ground for the messages. Understanding the English message is nearly no burden. Log Messages are Event triggers, either in code or in a developer's/admin's mind. If I get a log message in my native language I don't know which event that triggers, which makes it actually harder.
Really. I don't know any non-English person who considers log internationalisation a good thing. Fighting anglocentricism is a very anglocentric topic. Outside of UK/US that's a non topic. We (non-English people) are happy that there is a language we can use to talk to each other and we don't really care how it came to be that widely known.
And even if you don't speak English, I don't see the advantage of parsing \x03 instead of "Error:.*". Both are strings that have a meaning which is rather independent of its encoding.
When applied widely throughout a system, this leads to the internationalisation of log messages. Thus lessening the anglocentric bias in systems software. Windows has done this for years, at least with its own system logging (other applications can still put free-form text into the event logs if they wish.)