Well, technically it was on the builder to have the info engraved, so if anyone is in violation of the law, it's them and not you.
Thant said, on the extremely rare chance the ATF ever gets ahold of the firearm for some reason and finds it's not engraved with the proper maker's info, they may resolve it by engraving it themselves in whatever horrible place and way they deem fit.
For the second one, yes. You'd need a new Form 1, and since you're the maker on a "new" SBR, you would have to engrave your info.