I can confirm there isn't one there until the converter asked me to add 'x_utf_' to it.
My board is in English and it's not a very big database, just under 253MB. It didn't take that long at all to convert to utf8 and I ran both the options for conversion in case that may have been the problem but the weird table names happened with both of them after clicking "Finish" and brought up the database error on the board.
So I just changed the conf_global file back to the way it was and just left everything as it is, weird tables and all.
I have a similar problem. It runs the conversion no problem so I change the info in the config_database file - it all shows up fine on my board.
The problem arises when I click on "Finish". The converted tables change to exactly the same as hmikko's picture shows, and the original files are still named the same.
Thankfully I can just change the information back in config_database and I can still access my board. I ran the script twice - downloaded today so the latest version available - and that final step did the same thing both times.
I don't have a prefix on my tables so I don't know if that might be part of the problem.