Note that "real world truth" is something you can never accurately map with just your senses.

No model of the "real world" is accurate, and not everyone maps the "real world truth" they personally experience through their senses in the same way.. or even necessarily in a way that's really truly "correct", since the senses are often deceiving.

A person who is blind experiences the "real world truth" by mapping it to a different set of models than someone who has additional visual information to mix into that model.

However, that doesn't mean that the blind person can "never understand" the "real world truth" ....it just means that the extent at which they experience that truth is different, since they need to rely in other senses to form their model.

Of course, the more different the senses and experiences between two intelligent beings, the harder it will be for them to communicate with each other in a way they can truly empathize. At the end of the day, when we say we "understand" someone, what we mean is that we have found enough evidence to hold the belief that some aspects of our models are similar enough. It doesn't really mean that what we modeled is truly accurate, nor that if we didn't understand them then our model (or theirs) is somehow invalid. Sometimes people are both technically referring to the same "real world truth", they simply don't understand each other and focus on different aspects/perceptions of it.

Someone (or something) not understanding an idea you hold doesn't mean that they (or you) aren't intelligent. It just means you both perceive/model reality in different ways.