PCEngine-FX.com

Specifically the Japanese market including all variants and add-ons for the PC-Engine.
So far I could only find the total for the consoles but not the software.

No.  The only thing you'll ever get are guesses.

For software, no. Numbers from sources that seem official are all over the place.

For Tengai Makyo 2, there was a magazine that said 500k, while Hudson said 300k, the director said 200k*, and a tracking company said 160k.

PCE Magazines listed sales rankings every month, but they all had a system of "points" instead of giving concrete figures. The points were determined by dividing the actual sales number by a mystery-factor that they never published.

If someone made up a database of all the points ever awarded by one magazine, then found a rock-solid sales figure for one game, we could possibly determine that factor and multiply out all of the other games.

*I can't find the original, but according to a 2ch conversation, this statement from the director came from a three-way interview with Hideo Kojima, and the latter said at the same time that Snatcher sold 100k.

Very interesting, great project for someone, not me though   :-"