I'd say Typescript/JavaScript on the backend are a bad idea across the board. That's not really because of this conversation, just in general.

The comment about Typescript was really about JavaScript. It's a patch on top of JavaScript, which is a shit show and should have been replaced before it ended up forming the backbone of the internet.

Python, typed or otherwise, isn't good for anything past prototyping, piping a bunch of machine learning libraries together, or maybe a small project. The minute the project gets large or starts to move towards actual production software Python should be dropped.