Any messages installer generated will still be in English, any thing from generated by the system will likely be garbled depending on the OS language.
Or do I misunderstand the issue?
So in large I dont think this message is from installer but rather being mangled by it, which then question is why is anything non English system generated being allowed at this stage?
The reason I know for sure, this message is NOT from the installer is because the large RED portion there is no equivalent in English text nor the rest, so this message is caused by sistem + installer allowing system to interfere where no system input is required. (Im my flawed opinion)
However having said that, the beta installer is incomplete at best in my observation of its many bugs which have been passed on. The version check feature is non functional even in Stable releases.
This message a result of version check can be simulated if you turn off the Internet connection.
This message is a result of the version check if you click next (on versioncheck) and then back, then next again
In none of these messages (installer generated one can see any red text etc.