There's a critical edition of Vālmīki Rāmāyaṇa and there's one for Mahābhārata. Does Bhāgavata Purāṇa also have a critical edition?
If it does, maybe it will help answering questions like Questions regarding the number of verses in the Bhagavtam
Also, which recension of Bhāgavata was used for the ISKCON translation?