there are commands in game so you don't have to do that.
/aec edit <insert name of config here>
this "opens" a config in commands and enables you to add new values.
/aec add <insert AV value here>
this will add the currently held item to that config with the AV value mentioned. if you add an item that is already added it'll get overwritten with the new value.
this will save the config currently loaded. because if you so much as exit the map to main menu while editing you'll lose all your progress. :V so make sure you save. you'll also have to re-open the config when you save if you're not done.
This reloads all the configs and refreshes the aether values so you can immediately test the effects of what you've added.
although if you would rather just figure out the string values and do it by hand you can download nei and go into the options menu that appears in your inventory on the bottom left corner of the screen, then go into tools, then data dump then dump out a file for item values. this will give you a big spreadsheet of all items and their current item IDs which also includes their full string IDs. just search for the id of the item in game and it should be on the same line.