The images are too grainy to see anything. (add: edited photos better now.)
The point of an outer certifying envelopes and an inner ballot is to separate them after receipt and then count the now-anonymous ballots. Ballots would be retained for only a short amount of time - until they are certified and any challenge deadline passed, after which they would be destroyed. The envelopes might be kept for the same amount of time. No doubt retention laws differed from time to time and place to place. No doubt an election worker (or janitor charged with disposing of them) liked the foreign-origin envelope and salvaged it once the ballot had been removed. No jurisdiction would be storing ballots or envelopes after 60 years.
Add: the most commonly encountered ballot mailings are from WWII (dozens of them on eBay
all the time), both the ballot-request mailing from the soldier and the ballot-return envelope, often saved for the APO postmarks.