TN status rests on the professional employment, and study does not substitute for it. Whether particular coursework is compatible depends on how it affects that employment and whether the program includes any work component, which is a question for counsel on the specific facts.
Judge the study against the employment it sits beside
The relevant test is not whether courses are allowed in the abstract but whether the professional employment described in the TN case genuinely continues. A part-time evening program that leaves the role untouched is a different situation from a schedule that cuts the position to a fraction of what was documented. Describe the actual plan, hours and format, when asking.
Experience alone is not the stated substitute under this diploma-or-certificate alternative. In others the rule names a baccalaureate or licenciatura degree, or a licence, and a designation is not automatically a substitute. No expenditure cures a category mismatch: TN still requires Canadian or Mexican citizenship, a USMCA-listed profession, its particular qualification, and prearranged US work that is not self-employment. The engagement must remain professional, temporary, and outside prohibited U.S. self-employment; a Canadian may seek admission at a port of entry or use an employer-filed Form I-129.
A common error is assuming that a professional title cures months of routine production.