Being a software architect is a very difficult job. Few people can balance between business requirements and system design.
You need to know the story of the system, what it can do, and it is worth updating it. If you failed to do that, you will end up with a Frankenstein of a solution.
Therefore, when someone says that they receive an opportunity to be an architect just because they did poorly in their previous position, I am getting worried and most of the time I am right to be afraid.
The architecture is horrible, and the design is equally bad. Usually, those people come to you and ask you to propose things, but rarely listen to you.
So, the best thing to do is to state your opinion but let them burn and learn from the mistakes. After all, it was not your decision to make them an architect and fighting with the system and culture should be saved for really significant problems.