I guess that you can just look at the table structure of both seditio and cotonti and tell by yourself.
In your place I would not use so many converters. Just modify a chosen converter (look at the first one and the last one and merge them) and try importing directly to xenforo.
You might have some problems with users, I would just assign them new passwords - if you used Siena after security upgrade. If they have still md5 passwords then it should not be much of a problem.