Recently I came across "Dolt - It's git for data". Maybe it's worth a look.
It's not CSV based (but similar to mySQL), and not WYSIWYG.
Dolt does not track schema changes, however (= columns added, removed, renamed...)
But it does track the data changes you describe, and enables you to do diffs, snapshots, rollbacks, time-travel.
Try using version-control software, such as Git. You can then edit the file however you want, such as with your favorite text editor, and you'll be able to look at previous versions and the differences between versions.
I use CLCL - free clipboard app. It allows you to have "templates".
For example, when I hit the CLCL hotkey, tap T for Template, I know if I press 6 it will paste my email address, and 5 will paste my phone number.
It's a little confusing to setup, but worth it, and totally portable so can run from USB.
It sounds like you're looking for Org mode (website, quickstart, manual). Org mode runs inside Emacs, but it's practically a world of its own. Emacs is a free, cross-platform text editor with facilities to display formatted text and images.
no vendor lock-in
Org mode source files are plain text. If you look at them in another text editor, the fancy stuff ...
Emacs is a cross-platform, free text editor. It doesn't specifically support subtitle edition out of the box, but you can install the third-party subed package, which supports .srt and .vtt formats, and has integration with the mpv media player.
In Emacs terminology, remembering words that you've typed is called dynamic abbrevs. Out of the box, pressing Alt+/...
FreeOffice TextMaker supports read/write of rtf, doc, docx. Sometime they played with limitation to docx saving. Version of 2016 works fine and very fast, new versions works too. Just try, it is not free, it is limited freeware.
LibreOffice/OpenOffice Writer is too big weight for your tasks, I agree. It is mainly for docx (2007-2013+), doc (97-2003+) and ...
CudaText editor is not an IDE, but it supports plugins, and LSP Client plugin exists. With LSP plugin and LSP Server for C++ language, you will get partly what is needed.
Then CudaText can split single editor window to 2 parts (for the same file).
Menu "View / Split tab / Split vertically".