is it possible to save manually entered data locally for re-use?

Hello. I'm a newbie, so please make allowances. This may be a stupid question as it seems like an obvious need, but I did some looking around and did not find it explicitly addressed. I have a large collection of MP3 files, many of which are from fairly obscure sources. As a result, I find myself manually entering many artist and album tag fields. I had thought that it would be easy to save those entries to a local db or dictionary so that the added value would be available on the drop down scroll for edits of subsequent tags, but I cannot find a way to do that. After I enter the new values once, the copy tag/paste tag options can do what I need as long as all the selections that are targets for the common fields remain called up in the same view, but this doesn't work if the value is needed in a different or later view. Can this local save be accomplished somehow with the export function, through some other method, or is there no provision made for this kind of local storage? Thanks!

Dropdown lists are limited to the values found in the current selection.
So if you include a file with a correct value, you can select that from the dropdown list.
Any kind of database with a growing list of e.g. artist names becomes a nuisance if you have more than some 50 entries (do not take that figure literally) as scrolling down such a list is not really comfortable.
And you claim yourself that you have a fairly large collection, so a couple of a thousand artists would not be far off.
A large list would have to be loaded every time you go to the next track as it could be that a new file would cause the list to be updated ...
If you implement the list with an incremental search, you fairly quickly end up typing in most of the name anyway (with all the spelling mistakes at the beginning, so that you do not end up at the right entry at all) so that there are hardly any benefits.

If you have grouped your files in such a way that you load only files of the same artist then there is already a dropdown list available.

To get names more or less right, you may use the filter and the sorting functions of MP3tag to group similar files together.

Or you write actions that apply the same naming conventions to a particular artist. The list of actions may become rather long ... see above.