So now you have presentation logic, tightly coupled, spread over two places. You need to jump between two codebases to even have a clue about what is rendering on the page.
There's an example on their website where the header of a table is defined in the frontend, and the body is returned by the backend. If I wanted something as simple as switching the order of the columns, I'd actually need to create a new version of my backend endpoint, release it, change the frontend to use the new endpoint, then delete the old one. That sounds crazy to me.
I use nested templates the same way React uses nested components. The key is cascading the context (like props) down the hierarchy. Column order change? One edit in the table template; everything that includes it gets the update.
The "header frontend / body backend" split is a choice, not a requirement. I wouldn't make that choice.
So what if you have presentation logic in two places, if it isn't necessary, remove the second instance?
There are so many gains by not using a frontend. You've greatly reduced your site size, removed duplicated logic, a shitload of JS dependencies, and an unnecessary build step.