So, back when this game was given away for free here on gog, I got it and the Japanese Incentive DLC.

Yesterday I decided to install it for the first time (through galaxy) and I noticed that the Japanese Incentive doesn't show up anywhere in the game.

According to its manual, the game should prompt me on if I want to play it or the main game before I choose my character right at the beginning, but it doesn't.

Is this a Galaxy bug or did I miss something?

Ps.: I'm assuming the never ending game breaking bugs mentioned everywhere in this forum have been solved so I can play the game properly without fear, right?

Eventually. I haven't been able to focus a lot on a single game recently, but if I get around to it, I'll tell you.

Also, about my original query, Support has answered, it is a bug within Galaxy and it will be addressed in the future. Right now, one can download and install the DLC separately over Galaxy's installation.

I'm doubtfull it's only a Galaxy bug. IIRC I had already installed it without Galaxy and was not convinced.