No, the dictionary isn't wrong (though dictionaries reflect, rather than prescribe, usage). I was disputing your interpretation.
To put into simpler terms or paraphrase is to change the vocabulary, not the accent. So, had he said "I'd like some cheese please" in an accent the listener found hard to understand, it wouldn't be the terms he'd need to change, but the pronuciation - and that is NOT translation, but modifying accent.
Now, my take on this particular situation is that in all likelihood the speaker wasn't using particularly regional words - it was a national political conference, and it's probable that the speaker was using mostly standard English vocabulary, syntax and grammar - it was a reasonably formal setting, and in those situations people do tend to use a reasonably formal register - they monitor the language use around them. I don't imagine that he stood up and started waffling on in Doric, for example.
So it's maybe a combination of an unfamiliar accent, which the hearer should have expected, being in Scotland and all that, and a poor sound system. The Caird Hall is used for classical music concerts, so either is was having an off day, or it's an excuse.
The response from Mary Fee is daft - racism is bandied about way too easily, and its overuse can dilute the importance of what it really refers to. I think her response was pretty chippy, tbh - she should have taken the piss, and had done with it - as it is it makes her look daft.
But translate is a wanky word to use - had it been the sound system, then everyone would have had a problem, and "translation" impossible, surely. It implies that the speaker wasn't speaking English, and would piss me off too, tbh. But I wouldn't call it racism - I'd call it idiocy.
Blotted - am a bit rusty on current reading - will have a scout about and get back to you!