Thank you very much folks for your feedbacks, I really appreciate reading your stories, also I'm glad to hear that Steam versions can work perfectly, so I can continue to give responses in the Steam forum knowing it's not in vain.
I must say the TWoS mod makes the campaign play very realistic, even without Real Navigation and only with Auto TDC. I'm playing 2 different careers, 1 special where I 'spawn' in game to meet historical events (I have even made a guide for it), and 1 regular campaign where I didn't get very far: 2nd mission, British Coastal Waters, I found a small trawler and had the VERY bad idea to engage it with my deck gun in rough sea, not only that I didn't manage to sink it, but soon after I was chased down by 3 patrol boats...40 minutes later: end of the story
My impression is the AI is far more aggressive than in SH3, and I'm playing on easy settings for the moment...