Yes, editing (while SmartGit is not running) would be best suited here.

Maybe instead of creating branches, you should take a look at SmartGit's Standard window and its Feature commands.

ATM I would consider the likelihood of implementing quite low as the request seems to be very specific for your workflow.

The UI and documentation is in the preferences, page Low-Level Properties.

Did you already try all hints from https://docs.syntevo.com/SmartGit/HowTos/Running-on-WSLg.html?

The used GUI library (SWT) and hence SmartGit only supports one scaling for all monitors. SmartGit only supports images at 100% and 200% scaling.

It is there - see the Hamburger menu. You need to unselect the Compact mode.

Do you change all 35k files in the commit or do you have enabled to show even the unchanged ones?

By default, for a file log, the file is preselected in the Files view. Why hide all the other files?

If it is about commits, just select the two commits to compare.