Aging food in a pickling medium/paste for taste and/or preservation is quite common globally. Wikipedia as usual provides a nice overview https://en.wikipedia.org/wiki/Pickling
Not pickles, but if your family makes jam in Hungary, then it’s not unusual to have a few jars of decades old ones, made by a long dead relative.
We have a 20 year old plum jam we recently brought from the country house’s pantry.
True across Balkans. There are some fruits (e.g. apricots) which have a highly variable yield from year to year, so eating a 5+ year old jam (from a year with exceptionally high yield) is not strange.
