Seems like intl module documentation is referring for some other internal version of shifter other than git one, or possibly that functionality is on its way. Nevertheles I needed that functionality and there is what works so far.
UPD: Thanks for comment I did glimpse to pre shifter era builder, and find out yrb2json parser here in already javascript format. Seems I am only the one person for these years who was interested in this functionality into nodejs shifter.