Bonding CSST to electrical ground system
The pipe only needs to be bonded at 1 place, usually this is at the meter. If it is bonded there the entire system is attached to a grounding bond and would be legal.

The gas pipe is bonded to prevent it from becoming electrified by a short. It cannot be used as a grounding electrode but the grounding electrode system needs to be attached someplace after the gas meter. I would check there as that is where the bond is usually located.

If you have lead pipes I would want to drive supplemental ground rods and get rid of the lead pipes (I hope you don’t drink the water). The reason to have a pair of additional driven grounding electrodes is a good idea for what happened to a tract of homes in my area. All the old pipe was removed and new non metallic pipe installed. A customer called because getting shocked. I discovered she had no ground and the pipe was plastic up to the house. Their utility did this to every home and the only grounding electrode was the water pipe. After installing a pair of rods she quit getting shocked. If that same case happened to you your gas pipe would end up being your electrode not safe and a code violation.