Honestly, it doesn't seem that complicated to modify some of these rules as an option and it'd wonderful it they did this. It's a win-win situation.
High ground gives advantage? Single variable might solve that.
Backstab on/off? Same as above.
Shove as an action instead of bonus action? Sounds easy as well.
Only casters can use scrolls from their spell list? A bit more complicated but doable.
Can't cast 2 spells on the same turn? Don't know how they programmed, so it might be complicated... but I'm sure they can handle it.
However, I don't expect balancing in both modes. That very difficult fight where enemies had the high ground is now easier? Missing a lot of attacks cause there's no backstab or 100% chance to hit? Well... that's the traditional DnD that you wanted.
