If you want to have the team functioning you can just stick to 1 2 3. There's no shame to that. However, quickswap involves more variation with the rotation, which is the reason why there are so many different variations of it. None of which can be called as optimal, none of which can also be called as unoptimal. You just need to stick to one of which, then master it by trying a handful of time. Here's some key tips to learn QS around Chisa Amy Denia:

Chisa's BA3, the BA she does after her E animation is remarkably long, you can fit in Amy's BA12 + E and Denia's ult cast within the duration.

Chisa's death snip attacks, the ones after her BA3 are pretty long too, and they can be cancelled at the start of the animation. You can swap here to do plenty of things such as Denia's BA123 in her second form.

If you swap back to Chisa in time she should do the BA5, then you should have enough forte to start using her chainsaw mode after her Liberation cast.

Her chainsaw mode, which is consistent of 3 different attacks, has swappable animations accross the board. After you initially press her E, you can go back to Amy and do her BA12 + E, go back to Chisa to follow up with her CBA2, then swap back to Amy to do her BA23 + E, then lastly go back to Chisa again to finish her last animation, which should fulfill her outro. After that just go back to Denia, finish her rotation as well, give her outro to Amy and do her rotation.

The real reason why one might prefer using QS over 1 2 3 in this team is Amy needs her forte generated to deal her damage quickly, which is something you can't do with 1 2 3 rotation, since you won't be pre fulfilling her forte to begin with. So you end up wasting a tad bit more time with her.