Tourism and Government

In the tourism information page, with each civilization, the player has some modifiers:

• Trade Route
• Enlightenment
• Open borders

These reduce or enhance the tourism accumulated with that player each turn.

Then there is the Government modifier.

I read somewhere that each government has a proper negative modifier, that is summed with the opponent Government modifier, if the two are different.
I remember something like Fascism has a more negative modifier than Communism, which is more negative then Democracy, but all of the 3 are way more negative than the 3 Medieval-Renaissance one. Between those 3 there was an order, something like Theocracy < Monarchy < Merchant Republic).
So, in order to quicker get a cultural victory, one should preferably pick Republic and then Democracy, unless a lot of other player have the same governments, e.g. Fascism, in which case Fascism would be preferable.

Does this still hold?

In my game I’m Democracy, and I have Fascist at -40% (that’s a lot!!) and with 2 players that are a Merchant Republic at -20%.
If I switch to Fascism, the -40% will surely disappear, but would the -20% (with two players!) grow?
According to what I know, yes, but the player that is Fascist is my friend, and allied, and told me: “don’t worry, I have a -20% as well” (i.e. he, a fascist, with player in Merchant Republic has “only” -20% Tourism penalty)

What Government should I pick?

How does the Government Tourism modifier effectively work? Is my knowledge outdated?