My experience with Tcl is 30 years of using EDA tools, all of them equipped with this language from hell. Luckily, I've been to restrict the scripting part to the minimum. I'm sure that if you know the language well, you can see the foundational model that's behind it, but for occasional users, there's nothing predictable about it.

I couldn't tell you exactly all the thing that are wrong with it. Let's just say that a language where this is ok:

puts "Hello"

But this is not:

puts "Hello" # A comment

shouldn't exist.