Form One Questions

I’ve got two questions for European pilots regarding the Form One,
arising out of curiosity on my part.

First, it appears to this US pilot that one of the uses of a Form One
is to certify that a new part is airworthy, with the basis for
airworthiness being that the part was made in accordance with a TSO or
some other approved technical specification. Is this correct?

Second, why would a plane made in Europe not have a Form One for all
installed equipment? Isn’t it necessary to certify that all of a new
aircraft’s equipment is airworthy? I ask because my LS8-18 (made in
2000) has Form Ones for the 4-point harness, nose hook, CG hook, main
wheel hub and brake, airspeed, altimeter, VHF radio, ELT and
transponder antenna. No Form Ones at all were supplied for the
transponder, encoder, SN10, Sage vario or VHF antenna. It isn’t a
matter of loss, because I have all of the Form Ones listed on the
original LS document transmittal letter.

-John