I am wondering if informal methods of automatically extracting, transforming, and loaded data constitute "ETL." For example, I code Excel VBA to extract from databases onto a spreadsheet, transform the data into the desired format, and load by moving the Excel file to the correct folder. Would it be incorrect to showcase this as ETL for resume? Is there a term or lingo for this?
The process you describe is very extremely techinically ETL, though if I were reviewing qualifications with a candidate during an interview for a position that required what I usually think of as ETL experience and they described the process you mention as the "ETL" process they were familiar with, it's very likely that the interview would end politely and quickly.
It would be much better to describe this experience in terms of what it unambiguously is- VBA and advanced Excel skills are very valuable. You could call it "data preparation and processing using VBA and Excel," for example.
Calling these processes "ETL" experience is asking for trouble when an employer is looking for experience in one of the formal ETL tools or methodologies is unhappily suprised by the distinction.
ETL is not a tool, but the process or group of processes intended for data integration from a source system to the destination system, generally a Data Warehouse.
So if you are doing an extraction, transformation and further loading of that transformed data, you are performing de facto ETL. Someone could argue that it is harder to maintain, and more prone to errors. And they'd be right. But a poor code does not convert it into something different than code. Same applies.
The tricky part is the final load process in the sense of being moving Excel files in a file system. We use at work a MapR DB based on MapR FS made out of independent files and yes, we do data integration and we finally "load" those files into their final destination, despite they are actually just files. In the end they are accessed by a Query Engine. So in the present day I would consider it an heterogeneous database and your system an ETL. Don't see why not.
I believe what you are describing is technically ETL. However I don't think it is what people in the industry would typically consider as ETL. And Excel would not commonly be considered an ETL tool.
There is a difference between experience with ETL and experience with a specific ETL tool or product.
However I do think that if you explain yourself carefully that it would be beneficial to your CV. Eg: "Automated Extract, Transform & Loading of data between databases using VBA and Excel" is honest and unambiguous.
In my opinion it shows a degree of understanding, technical proficiency, problem solving and experience. And I think that has merit.