"as a non-prototype trust account,"

Non-qualified.

https://www.irs.gov/retirement-plans/non-governmental-457b-deferred-compensation-plans

Also called "Top Hat" plans with "rabbi trust." That description from the client isn't quite right.

There would be reporting on W2. Not 1099-R.

"In the plan documents, look for the distribution options. The default distribution option for a nongovernmental 457 plan is a lump sum distribution within 60-90 days of severance from the employer. Also known as separation from service, this means you get ALL of your deferred salary reported in a W-2 in a lump sum in one tax year."

"The issue with Medicare and FICA taxes is different than qualified plans. Since this is considered deferred salary, you must pay Medicare and FICA taxes if owed. In addition, when you get distributions, you are issued a W-2 by your employer rather than a 1099 as from a qualified plan.  Usually the salary you defer is above the wage limit for social security, so you just pay the 1.9% FICA tax upon deferral."

I was reading this just last week: https://www.fiphysician.com/non-governmental-457b/