You don't restock your hand of cards, you restock the four money cards on the board which are available to take, the same way you restock the tiles available to buy. That looks consistent with the English and German rules; I would assume the Dutch is the mistake, that they meant until each supply has four cards/tiles.
I would say the English and German ...
As far as I'm concerned, your intuitions through play are correct. Redesigning your Alhambra is an action of last resort, rather than an action a player is likely to take multiple times per game. Quite often I don't redesign my Alhambra at all during the course of a game. If you can construct a reasonably expansive Alhambra where it is easy to add new ...
Here are summaries of five of the Alhambra expansions with links to detailed video reviews by Tom Vasel. He gives opinions on which ones are the best and which ones are not worth it. I've included some highlights from each video. I recommend watching and deciding for yourself. All quotes are from Tom Vasel.
Expansion 1 "The Vizier's Favor"
From my experience, early leads in Alhambra tend to not indicate victories. In most games in my circles I am last after the first scoring round, and then win the game.
First scoring round is all about walls. These walls if played right
will make you points two more times in the game. The color points
are meager, and the game will change ...
You only get the points for first place. There simply is no second place person to receive those points. If a game wanted to let you get the second place points also in that case, it would need to be spelled out as a special rule.
Quoting from the rules on second round scoring :-
"points are awarded to the players with the highest number and second highest number of building tiles of each type."
Later it says "You must have at least 1 building tile of a particular type to be awarded points for that category".
So lets say you have 2 pavilions and the 2 other players have 0. You ...
Assuming everything else in the rules is the same as the English translation (i.e. you adding cards to your hand ends your turn), it would make no sense to also "restock your hand to four cards from the supply". So, in agreement with others, I think the Dutch must have a mistranslation.