Yeah, I've gone through all other paths on Regina route, I must say I got baited a bit. In the end, the only thing that changed is if you do "wrong", you'll get deeper inside in the last cg. Also to sleep under her in a scene you mentioned you must play trust with her instead, otherwise MC will be too scared to do that. And to make her prevent attacking Naya you must do brave and trusty, also tell that maybe there is another way.
I also noticed that in the last scenes we can't go scaredy cat anymore. There is simply no option, and it really sucks. What was the point of all this being afraid path throughout the route if it just vanishes in the end? Was it all about that one choice to confront Regina during fight with Naya or what?
UPD: never mind, that line keeps going if you choose to agree about war. Kind of vague, but at least Artical did not completely abandon it. I still wish to keep on about all this giantess trauma, even if it slowly turns into MC's masochistic fetish. Fun fact, that might be the only route in which the one who gets brainwashed is MC.