I don't think it's a problem because it isn't the brick that is making the house weather tight or anything, it's a surface application.

I agree with pal.

Why does it seem problematic to you?

I worry that fypon molding on top Of tyvek isn't much of an exterior shell for our weather.

Sounds like what you are referring to is frieze board. Normally used to transition from brick to softit/fascia. The frieze board will sit in a brick pocket which helps to prevent air flow in attic and also to stop bugs from getting into the attic as well. Sounds perfectly normal.

" brick will not go all the way to the roofline"

It rarely does.

It is not placed between roof rafters, and has steps on eaves.

The trim is to cover up these areas and make them look finished.