An interesting thing about osx shortcuts is that you can change almost all of them with system prefs -> keyboard -> keyboard shortcuts. (for programs individually and for the whole system)

It seems you haven’t noticed that there is a Command key both to the left and to the right of the keyboard, so Command-[ and -] are pretty easy to do one-handed if you use the Command key on the right. I think Ctrl-Tab is just there for compatibility with Windows browsers that use that as their main tab-switching shortcut.

Oops! I use my left hand for keyboard shortcuts while the right hand is occupied with the mouse so didn't even think to look for Command or Option on the right side!