So I recently played through Divinity: Original Sin EE and was using Kruulos Achievements Guide "D:OS EE Achievement Guide / Walkthrough" which worked out very well!

Except the "Tactitian Mode" and "Honour Mode" achievements I did all in one go. Nevertheless I realized that there were some achievements which you can easily miss in your first playthrough although you were following the guide.
To be "Forgiving" or "Independent" you have to watch your answers in all those little conversations, which I did not really pay attention to - in the end it was close but I got some dialogue options to go in the right direction.

Those are:

• Sister of Mercy (you need to be "Forgiving")
  
• Father Lucifer (you need to be "Independent")
  
• Wolfpack (you need an unspent talent point in the end of the game)

Plus the already mentioned difficulty achievements which require multiple playthroughs (and I cheesed those with a savegame since I didn't feel to play again or do the barrel speedrun):

• Tactitian Mode
  
• Honour Mode

For all of those who missed the achievements, here are my savegames you can use:

https://drive.google.com/drive/folders/1GYPNRGVJz6lZcYS92Of2m7nyNsXjgZj9?usp=sharing

(Using the Honour Mode savegame will also give you the Tactitian mode achievement)

The savegame for the difficulties I've used is not from me! It was uploaded to Savegameworld, here's the original source:
http://www.savegameworld.com/pc-divinity-original-sin-savegame/
Thank you for sharing, noble player!