One thing this reminds me of from when my kids started to talk is this – we’d keep thinking they said a new word, say ‘table’. Then we’d agree there was no way they could know what word or have said it. Then, a few days later we’d hear it again, clearly and in context, and then we’d realise they had said it the first time. So I stopped being judgemental about what they said and just believed everything I thought I heard!