True, and pretty sure this is what the question asks for (although I agree it is badly defined).

There is:

From the documentation:
https://www.postgresql.org/docs/9.6/arrays.html

Why is this lower ranked the valid paren kata?

There's a rank breakdown in your profile, even without CW Red.

Only with CodeWars Red subscription, AFAIK. (you can check my profile what it looks like)

So I ranked up to 5 Kyu doing purely SQL katas. I'm good with that for now, and I want to switch over to some Python training. Is there a way to keep track of Kyu level in different languages like Python and SQL?

This looks really clever. Where is this functionality documented?

SELECT matrix[j][s]

The problem should say to return float.

Yeah very confusing

Some kata support Python3. There is a version selection box on all kata, but if 3 isn't supported it will be greyed out.