I don't see anything wrong with keeping the 'Annals of Aman' + 'The Grey Annals' + 'Tale of Years (WotJ)' in our (flat-world) conception.
Of course, we could (and should) add bits and pieces from other works when we have evidence for their chronological place, if it fits our 'flat-world' framework.
I wasn't suggesting any fanfiction with my 'Chronology of Arda'
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Though I would go further than Gondowe, and extend the 'Chronology' into the Second, Third, Fourth, and even further Ages (as long as we have textual evidence that fits TNS criteria, that is).