While striving to get some assistance with the inner workings of Embjer.js as in use by Vault - I reached out to some folk on discord embjerjs (#help room) - and I was informed that portions of the framework in use require upgrading to more recent methods / conventions including for example the use of partials:
https://deprecations.emberjs.com/v3.x/#toc_ember-partial
If upgrading to EmbjerjsV3 will is being considered then it may be better to convert all partials into reusable components.