Relational is not the same as “relative” in the common sense of that term. It does not mean that all statements are equally true because they are all “relative” in some vague way. We can make all the usual claims about factual and logical truth so long as we understand the contextual frame we are referring to. In general, we don’t even need to specify the this frame since we all share the same world. If I say “unicorns don’t exist”, you assume I mean “in our shared physical reality”. I only need to specify the context where it varies from the default assumption, for example if I meant “in Persian mythology”.