hebrew date on the plaque is 1 day off the expected date. English date of June 9, 1988 could be either 24 Sivan (before sunset) or 25 Sivan (after sunset).
The plaque has 23 Sivan which seems too early.
The grave has the same English date with no Hebrew date. https://www.findagrave.com/memorial/59570080/arthur-katcher (Sharon Memorial Park)

So we have to assume the plaque has a typo.

E. Ganin Aug 2026