Honestly I don't even know if they were taking Pre-Crisis into account (that design for Supergirl makes me think of Matrix first)
But yeah that whole power scale got a lot of criticism for making no real sense even when it was first out. I really don't know how many of the folks here they even put into anything resembling what a real scale would be. And almost every heroine there has a lot of "Ummm" to their powers.
Molly's most likely over 3 tons but in fairness her powers aren't really physical (they're mental) and given what she's done in Runaways including flipping a Kaiju sized monster (who was as big as a skyscraper...) 3 tons is probably way under for her etc... though in her case it depends on how ready her mind is as she had to have extra help from Nico to not get sleepy. And so forth.
I don't think even when she was depowered as an "Atlantean" that Karen was ever even in the 50 ton range since her power was still treated as in the range of a Kryptonian during that time barring whatever silly weakness she had like "unprocessed materials".
And yeah ever since Kara's return they've been portrated as near equals with Powergirl generally a bit stronger.