Semantics are actually quite important. If you want people to understand what you're saying (without having to use 80+ posts to clarify your meaning) then you should use the word that actually means what you're trying to convey, not some other word that implies a completely different concept.
Of course, you're right. It's hard enough getting people to concentrate on the idea, rather than the words.
I doubt it. You're already streatching it with a "ceasfire", although that is within the realm of possibility. If you go to "cooperate", as in "work together for a common goal" as opposed to "just not fight each other right now since I have more important things to be doing" then you run into the problem that Guts would never, (and should never) trust any Apostle enough to work together with them on something, and especially if that something was as important as Caska's life. He wouldn't work with them because, if for no other reason, he'd be convinced that by doing so he'd put Caska at greater risk. This is even more true for Femto. And while maybe you could dream up some scenario where this wouldn't apply, it would be on the order of "what if the sky turned green tomorrow?" Maybe theoretically possible, but so unlikely as to make any discussion/speculation on it totally worthless.
Technically, the sky can't turn green because of the light, the water droplets, and the differences of wavelength between blue and green, making it a violation of the laws of physics.... you know, if anything, the sky would be purple, but our eye isn't that receptive to that color.
You think of course that Gutts would be unwilling to trust any apostle with Caska's life, even if that which is lost by not doing so is Caska's life itself.