"No extra tax" means no early-distribution penalty (excise tax).
Changing the code to G is improper. Code G can never be used to report a Roth conversion which is what the code-2 Form 1099-R is reporting. Your traditional IRA contribution that resulted from the recharacterization of the Roth IRA contribution must be present either as a deduction on Schedule 1 or as nondeductible on Form 8606. The Roth conversion is required to be reported on From 8606 and changing the code to G will cause your tax return to erroneously omit this.
Your Roth conversion may or may not be taxable depending on the calculations on Form 8606.
