Copying a loyalty ability doesn’t add or remove loyalty counters from any object.

If the loyalty ability has −X in its cost, the copy uses the same value of X.

The triggered ability of Chandra’s Regulator and the copy it creates both resolve before the loyalty ability that caused it to trigger. They resolve even if that loyalty ability is countered.

You can’t pay more than once for each time the triggered ability of Chandra’s Regulator resolves.

A Mountain card is a land card with the subtype Mountain, not any land card with a mana ability that produces red mana. Land cards are normally colorless, even if they produce red mana.