They looks very similar by facially by craniologicaly and by pigmentation,maybe coon keltic nordic is not necessary just a bit differentiated sub type of north atlantid(northwestern of other anthropologists)
i found some thinks logically, first keltic nordic is said to be nordic-noric or/and dinaric mix.dinaric has higher skull than nordic so noric race is also higher skull(at least the same as nordic) than nordic so if nordic and noric mixes it produces a higher skull or same skull as nordic but keltic nordic said to be lower skull than hallstat.and ifther is alpine mix alpine also nearly the same skull height maybe higher than nordic(look at lundman nordens rastyper gotatyp and alpine hli is given).so keltic nordic is not mix with nordic-noric or dinaric logically .so the people we think keltic nordics are i think nordic-meds or subnordics(nordic-alpine) or maybe nordic-subnordicmix in britain
I don't see any reason why a stabilised low-skulled end couldn't have derived from the particularly low-skulled North-Atlantids and or Gothics influenced from invading continental Dinarids. The pressure in the Atlantic for whatever reason is a lower HLI.
Alpinid/Alpinoid influences on the Keltid skull additional to the Dinarid were theorised by Coon though.