If we leave the slang aside, could it be that “truth” is a judgment like beauty or goodness?

Why not? I didn’t understand the question.

I don’t know; I read this in Rabbi Dessler and wanted to know whether the Rabbi agrees with it.
Usually people relate to a statement as “true” in an absolute rather than a relative sense.
For example: the statement “There is a God” is both true and not true.
He does not “exist” like all existing things, because “existence” is a created property; but if we say “God does not exist,” that too would be true—but a “lower” truth.

Do you understand what you read there? Do you have some side to think he’s wrong? What exactly is the point of this question?
No statement is both true and not true. You’re simply using the term “there is” in two different senses. [By the way, I also don’t understand what it means to say that existence is a created property. A property is not an entity, so it isn’t created. Existing entities are created, but not existence itself.]

Apparently the meaning is that the concept of “existence” is found only in our consciousness, and that concept can’t be attributed to the source of consciousness; about that source nothing can be said.
That’s a Kantian statement.

I lost you.