Indeed, I admit that "vouched" is too strong. He just let his name be used to legitimize the enterprise, and (like the other chief officers) did not see anything wrong with it until after the CEO ran away. Only then did people read the "prospectus" critically and noticed that there never was a real business plan.
I do not think at all that Andreas was conscious of the scam until that time. Also, as a tech guy he could be excused for not noticing the financial problems (unlike economist Tuur Demeester). But the episode does not inspire confidence in his competence as auditor, does it?
Or as was quoted above he had no access to finances, how can you possibly judge his competence as an auditor based on an
advisory tech role working away from the office and having no contact really other than the occasional Skype call. Again this is in the blog.