回答
This is not a piece of advice to you I'm talking to myself for my practice of writing skills.
I can't grasp it so, I can't tell about it at all.
I suppose in the sentence ② the phrase '(discuss a discuss a subject)' might be grammatically strange.
I suppose both①② sentence 'when' clause would modify the verb( don't like talking )phrase.
I suppose the word 'unnatural' might means the thought the theme should be in the main clause.
This is not a piece of advice to you I'm talking to myself for my practice of writing skills.
I can't grasp it so, I can't tell about it at all.
I'd like to reconfirm the second question sentence.
When they discuss a discuss head-on, they don't like taking around it. I'd reduced one phrase 'a subject'. is it right? if it's so, it may be a hint. this is my idea, the theme 'a subject' is in the main clause of the first sentence, but in the second sentence the theme is in the subordinate clause.
I suppose the word 'unnatural' means the thought the theme should be in he main clause.