When I try to export a deck from this site for MTGA I get something like this:
4 Ashiok, Dream Render (WAR) 228
2 Chemister's Insight (C19) 80
4 Didn't Say Please (ELD) 42
4 Drown in the Loch (ELD) 188
4 Drowned Secrets (GRN) 39
10 Island (GN2) 57
4 Merfolk Secretkeeper /// Venture Deeper (ELD) 284
4 Murderous Rider /// Swift End (ELD) 287
4 Overwhelmed Apprentice (ELD) 60
10 Swamp (GN2) 59
4 Thief of Sanity (GRN) 205
3 Thought Collapse (RNA) 57
3 Wall of Lost Thoughts (RNA) 59
4 Aether Gust (M20) 42
3 Clear the Mind (RNA) 34
4 Cry of the Carnarium (RNA) 70
4 Ritual of Soot (GRN) 84
This causes multiple errors when trying to import into MTGA. The same deck in MTGA exports as this:
Deck
4 Ashiok, Dream Render (WAR) 228
2 Chemister's Insight (GRN) 32
4 Didn't Say Please (ELD) 42
4 Drown in the Loch (ELD) 188
4 Drowned Secrets (GRN) 39
10 Island (ANA) 62
4 Merfolk Secretkeeper (ELD) 53
4 Murderous Rider (ELD) 97
4 Overwhelmed Apprentice (ELD) 60
10 Swamp (ANA) 63
4 Thief of Sanity (GRN) 205
3 Thought Collapse (RNA) 57
3 Wall of Lost Thoughts (RNA) 59
Sideboard
4 Aether Gust (M20) 42
3 Clear the Mind (RNA) 34
4 Cry of the Carnarium (RNA) 70
4 Ritual of Soot (GRN) 84
The fix for these seems pretty simple. For the MTGA format, don't write the numbers at the end, which will produce an error when they are wrong, and don't write the second card name for Adventure or 'choose one' type cards, which will also produce an error.