This is the main point we discussed, too. But sometimes you’ll find that a little variation is as I said simply NEEDED. Period. It’s the case of translation errors or script errors. They are rare, but, still, present (at least in the italian translation). Sometimes you’ll find that what works on text doesn’t work on voice and vice versa. You will discover that even in the original english voiceover there are a few discrepancies with the script.
When you notice all these things, while working on the project, you gradually become more and more tolerant to little discrepancies.
Not to mention the gag of the tea, in which the playable characters speak different languages. We discussed it with Ron in a private section of the forum, and we agreed it was better to transform the lines originally in italian into another language, even if the subtitles weren’t inconsistent.
And I also think that the majority of people who will play the game with your german fandub will turn off the subtitles. There’s no point in having subtitles for the very same language you’re listening to.
Oh, yes, the final localization is up to you. This implies a certain degree of artistic freedom.