Concerning this, the MjE theme doesn’t support any custom fields extension or adding field through the back end.
Technically you can add more custom fields to user’s profile but it requires knowledge of WP. Please consider to hire a web developer and remember that the results might change the display of the site.
It’s such a pity but there’s no further support that I can offer you on this matter.
I totally understand your concern about this problem.
As the matter of fact, the MjE version 1.1.2 was in progress while we’re collecting showstoppers so there will only be some essential changes in the admin area and improved features.
However, this will definitely be improved in version 1.1.3 (both mobile and desktop version) same as improving the checkout flow. We will certainly give our best performance to offer this version as soon as possible.
I express my regret for any inconvenience this may cause and I appreciate your understanding, patience on this matter.