Hello and welcome to the forum.
Why do you want to switch to Mac App Store?
If you search the forum you will find it is not best option. the wisdom of the forum is that You are safer to stay with what you have outside the forum for a number of reasons. 2 include:
There is a delay between getting update here and for it to appear on the apple site.
Apple take a cut so there are not as many in app purchases so most of what you want have to be purchased from the Accordance site anyway.
I have been a member since 2011 and made lots of purchases and not had any issues with the official Accordance site.
Edited by ukfraser, 01 January 2018 - 02:07 PM.
Accordance 3x on iOS 13x on 1st gen iPad pro and iPhone 8, occasionally accordance 13x on Mountain Lion on a reliable '08 mbp.
Other life enhancing software I use includes: forScore with AirTurn page turner for leading all aspects of a service from my iPad including liturgy, sermon and the congregational singing; HymnQuest for developing my selection of appropriate music for the service; Sibelius for preparing the music scores; Lightroom for my photo library!