My understanding is that when otherwise excludable employees are tested separately for ADP/ACP the coverage test must also test otherwise excludable separately.
Any ideas on how should this be reported on the Schedule T if an exception does not apply?

The instructions to the Schedule T indicate that an employer is permitted to treat a plan benefitting otherwise excludable employees as two plans, one for the otherwise excludable employees and one for the other employees benefitting under the plan. You can then use line 4e to report the disaggregated part of the plan and either the ratio percentage of the exception.

I think the biggest problem is how to code them.

The instructions only say to code things using
401(k), 401(m), nonelective.
there is nothing to say that you can describe them as
401(k) otherwise excludables, etc.
Hyperprep won't even allow you to type that many characters.

I think we have simply been using something like 401(k) OE

pjg: very good, you are correct, if you test ADP separately you must test coverage separately as well.