Same here about finding resources for language design.

I wish there was some course that could teach me language design so that I can (better) predict how my decisions will affect the final result.

Plus how much can reasonably I "pack" into the language [1] in terms of notation and cognitive load when used.

Maybe some resource about choosing notation would be nice too (as opposed to parsing notation once chosen). When I try to pick many ideas from different places, I'm sometimes surprised by collisions in notation.

In general, I have to idea in what model I have to run my estimates.

What are some examples of consequences taught through the course you linked to?

[1] I'm talking about textual languages only for now.