Does anyone know what is the relationship bettween the FIS race points
(going up with worse performance) and the FIS point rankings (gong
down with worse performance)?

One who cares about numbers,

RO

You are confusing oranges with bananas here.

One thing is the FIS ranking, used for determining athletes start
lists, the other is the World Cup rankings, which are the ones who
counts at the end of the year.

The FIS rankings, similar the ATP rankings, is composed only of the 5
best results of the past 12 months (the FIS list, however, are not
updated weekly, but using some criteria that I don´t really know).
After every FIS race, there is some Penalty points that are used for
calculate the FIS rankings. In this case, we can call the "negative
points system".

The FIS World Cup Rankings are composed by the sum of all WC events
along the CC season. The WC races, like Formula 1, give points for the
racers according to their position. In this case, the more the better.
The best overall CC skier is the one who acumulate more points (only
at WC races) along the season. This will be the "positive points
system".

The relationship between the FIS points and the FIS World Cup points?
None. You can be the best skier in the FIS rankings because you were
great in a couple of non-WC races and don´t collect a single point
during the WC races.

After all that, and making a little more confusing, there are some
skiing disciplines (like snowboarding) that use the positive points
system for their FIS rankings and qualification system, so you might
be reading the points system in another area.

I hope I helped a little bit and didn´t confuse you even more.