Hi Thibault,
Regarding the Filter parameter screen in Query activity, the problem is that this fields form is quite buggy with special characters management, often it generates bad escaping chars; so the best is to use the Advanced editor to circumvent such issues;
Often with direct type in field, backslash are added.

appears as:

when line is selected, and appears as this when you are in the field:

The same for the Value to this:

appears as:

Then, it should resolve your issue about boolean type, because I guess Adobe Campaign is misleaded/wrong issue reported.
Regards
Jean-Serge