Like almost every other school that provides institutional need-based aid, Wesleyan treats international applicants that are seeking need-based aid different than U.S. applicants. I would say that your first statement that you refer to above is mostly correct, with the caveat that international applicants face higher scrutiny earlier in the process.

Self-employed people generally take business deductions, like cell phones, gasoline, car leases, depreciation, and others stuff, that schools will add back in. So one parent may be deducting $10k-50k or more that CSS schools will add back in…so a FAFSA income may be $80k, but CSS May consider the income as $125k or more.
Someone in this situation may want to run the college NPC twice to get a range of possible net prices for the college: one run with income as normal, and another run with business deductions added back to income.