As someone who has trained as a translator and interpreter, this is a bit hard to tell, because the surrounding context can change it entirely.

"General valmore". Is the way this is said just oozing with contempt in the original, or using the honourable title in some ironic way?. The same way you might say president biden, or 'madam' to a to someone insisting it's 'ma'am'. Then 'great' general with quote marks could well be pretty close

"do as you like". Has threatening already been established in this scene, is he here to behead the other and is that established elsewhere? Then this 'my head is not so easily parted' thing is more acceptable. Remember also that Japanese is a less direct language, while English is more direct, 'American' even more so. Spelling it out more clearly is fair as part of a translation into American English from Japanese.

I've worked with a very blunt/direct language or two and going into English which is more middle of the road by comparison you have to do the opposite. Because otherwise it comes across as rude when no offense is meant. And going from English into those languages you have to cut out some of the circumspect bullshit and just get to the point, or else they look shifty and evasive.

Looking at the art, I can absolutely believe the original was trying for some ye olde flowery nonsense also. Were they?

TLDR: Making it more 'blunt' and spelling things out more clearly is appropriate, particularly with Japanese being quite indirect. And we'd need the surrounding context to more accurately judge if these are fair. A single line doesn't tell you much, and its hard to judge. They're not inserting their own politics at least. I'm not saying you are wrong and that they haven't veered too much into creative writing, I don't know enough Japanese to tell. I am saying I need the surrounding lines to better judge.