I don't see where the parens are on the keyboard. No number row. Is it another shift/fn level down?
I think it's a strange choice not to have them be first class, unshifted characters - and yet have such a dizzying array of modifier keys.
I also think that the keyboard was likely designed to be familiar to those comfortable with the standardized keyboard layout, as opposed to being efficient.
From an efficiency perspective, there's a lot that you can improve on, both in the general case (layout for English typing) and in the special case of Lisp programming - but I don't think that was their goal.
I wouldn't buy one of these myself, but I can understand why someone else would.
As a software hack, there's always Shift Parentheses[1].
[1] https://stevelosh.com/blog/2012/10/a-modern-space-cadet/#s17...
On any PC keyboard, just swap parentheses with square or curly brackets. That is way more useful even if you never program in Lisp. One of several things the Lisp Machine keyboard layouts did well.
Also, tiny keyboards are usually programmable, so the key labels might not be correct. If your layout is custom enough it becomes very hard to find keycaps which match the setup(and basically impossible if you don't want to wait >6 months).