Yes, in 1.38.3 the library slot is not rebuilt.
I.e. it needs to be rebuilt, right? Will that suit the majority of the community?

According to HeroesWorld rules, there are no restrictions on rebuilding the library. But this is a case where players use the checkbox by mutual agreement. They play both ways.

ideally it should be equal to 0.

OF COURSE! I've been saying this since the WT times.

For example, does anyone play without the chess timer now?
does anyone disable the "start timer after committing turn" checkbox?
what about the "replayable quick battle" checkbox?

I think 100% of HeroesWorld players play exactly like that.

So which checkboxes should not be in plain sight?

almost all players disable the cartographer, hill fort, and key guardians' tents. These checkboxes can be removed altogether. Impose a ban on these objects in HeroesWorld ruleset. However, when playing without rules, they should appear.