Multi Currency (data consistency issues)

we had found out when we used Multi Currency, amount are not same when we tried to upgrade latest version


Newer versions have completely rewritten general ledger engine based on what I’ve learned over the years. As far as accounting behind Manager goes, it has currently bug-free status while version 20.2.88 had old general ledger engine which had quite a few bugs - both reported and unreported especially in multi-currency and inventory modules. This means figures in the latest version would be considered correct.

How can I explain my users, without proven facts, latest version is correct?