At best, sheet music is a 'shorthand' for what is actually played. If you want every nuance from a pop tune or gospel tune, whatever, written out verbatim, the music would be unreadable! Phrasing isn't always militarily neat, pitch is never exact (unless Auto-tune'd to hell!), rhythm is never easily annotated.
And that's just 'at best'!
At worst, it is little to do with the tune you want to learn!
You have to remember that you didn't buy a score... you probably bought a piano reduction. So firstly, expecting all the instrumental parts, particularly the bassline, to be exact for the record is optimistic at best. These song sheets are re-arranged so that players of a limited skill can play them. A full Jackson's bassline would be beyond many pianist's abilities just by itself, let alone what the RH has to play!
Then, you never know what the transcriber had to work with. Was he given the pop single, was he given the work the way it was demoed, did he work from the album version, or a remix?
Maybe, if you want precise charts, it's time to get around to charting them yourself? If you can read it, you can write it. Or maybe simply do what your choir seems to be already doing it... just learn it by ear off the record..!
That's the best way, anyway!
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An arranger is just a tool. What matters is what you build with it..!