Its regarding Issue #10557 in jabref . you can find the link here
Store journal lists in separate directory · Issue #10557 · JabRef/jabref · GitHub. you can go though it .
for above issue created a custom file from jabref preferences and added some journal abbreviations in the test.csv file using my local excel . I can see the values from my local excel in to my jabref preferences.
As, shwon below images .
but I am unable to add abbreviations by using “+add abbreviations” . they are not saving in my test.csv file. what can I do so that it would work.