Should I amend my taxes filing if I forgot a 1099-R but taxable amount is $0, a normal distribution?

It is always best to have all of your information on your tax return, even if there is no apparent tax consequence.  However, a non taxable pension may affect your taxability on Social Security.

If you do not file an amendment you may get a tax notice describing the effects of any change.  This may take 6-9 months.

You could then review the change and make any adjustments necessary.

Please understand that a tax notice does not put you on a black list.  This is a technical situation that happens frequently.  It is not a criminal offense.

Or, you can prepare an amended return and see if there is any change before you mail it.