funding valuation and 401(a(26)

just wanted confirm my understanding that if a plan does not provide meaningful benefits to enough eligible employees for the plan year, but then adopts an amendment after the year end but before 10/15, that this does not impact the valuation for the year preceding the amendment. For example, 10 eligible ees and only 3 have meaningful benefits for year X.  In year X+1, a timely amendment is adopted to correct the (a)(26) error for year X. There is no change to the valuation for year X and the 5500 for year X, yes?

Sounds like the -11g amendment is getting adopted more than 2.5 months after the end of the plan year, so you would indeed not see it in the valuation results for year X.