If you like what is presented in this article, take a look at Grafana Tanka (https://tanka.dev).
The environment could be enriched with some handy functions for working with structures. They could just be normal JavaScript functions. For example, a version of Object.assign which understands that "key+" syntax in objects. Or a function which removes entries from arrays and objects if they have undefined values, making it easy to make entries conditional.
Those things are simple enough to write on demand that this might not even have to be a packaged tool. Just a thing you do with npm.
The stdlib is also pretty sparse, missing some commonly required functions.
does it really though? what part do they struggle with?
This seems to be the general curse of template languages. For some reason, their authors have this near-religious belief in removing every "unneeded" feature, which in practice results in having to write 10 incomprehensible lines of code to do something that could be easily done in one line of readable code in a proper PL.