I notice you've used two different programming languages to express application logic. A the high-level, you have automations, which are simple but look very limited in terms of capabilities (i haven't studied this part in great detail, but does its support things like looping, arbitrary conditional expressions, and an abstraction mechanism like user-defined functions?). At the low level, you have JavaScript to do fi…
Automations are simple by design - the general automation steps are kept simple so they are easy to configure and create. We do however have a JS and a bash automation block. These blocks let you perform looping, iteration and logic using either JavaScript or bash.
The reason we use JavaScript is simple. Most software engineers can write or at least express simple constructs in JavaScript. Being a C family language, this makes it easy to pick up for engineers who have been exposed to other languages like Java, for example.
The problems you are describing are actually something that we have felt before, when budibase did not have JS support, we had users reporting that the templating/handlebars syntax was not good for logic, and was new to them. It was esoteric and required in depth knowledge for advanced use cases.
Using an off-the-shelf high level or more specific expressive language has some serious drawbacks, especially if you create it yourself. The first is education - writing extensive docs around how to write and use that language. The next is maintenance - maintaining your own custom PEG grammar or programming language is a huge project in itself, not even including the research required to execute it well.
By using JavaScript, we can leverage the already existing plumbing for executing JavaScript, and provide something that has much for familiarity to the general user.