Getting out of Colditz was only step 1. Once outside the camp, the ability to act your chosen cover would have been an item for consideration, too.
So, speaking German or French without a British accent likely would have been a pre, as would being familiar with the home town of your cover.
Also, they would be reluctant to let their top craftsmen go. If you were really good at falsifying passports or ID cards, for example, your skills would be useful to keep around for future escapes.
