Then it's a problem.
Wow, someone actually trying to interact with an autistic person in a way that makes sense to them. There's something you don't see every day.
wait, trying to understand us, instead of forcing us to understand THEM?
damn, she could go far.
I remember reading about self-harm problems from the mother of a teen non-verbal autistic at the blog "Mother of Shrek".
Just guessing and trying to understand.
Well, if someone is non-verbal (especially if spoken language isn't understood), or at least has difficulty in speaking/understanding speech, and they're already stressed out about something (whatever that may be), having someone talk and interact in ways you don't understand, or if you do understand but it's simply overwhelming, can make it difficult to keep calm, which makes it difficult for someone who self-injures to stop it.
For instance, even though the development of my speech, to an outside observer anyway, has been more or less typical, it is stressful, and when I can't do it, having people continually prompting me to use speech, or consequently not interacting with me because speech is one of the few ways they know how to communicate, will stress me out, sometimes even now to the point where I bang my head. Nowadays at least most of the time, when I have a hard time to keep myself from self-injuring, I can mostly control it enough so that I bang my head against things like pillows instead of things like windows, walls, and metal bars.
In fact, the best way to diffuse a situation where I am injuring myself is when the other person / people around me resist their NT instincts of how to handle it (such as looking at me to show concern, or touching me, or speaking in frustrated or angry tones, etc.) It's best if the other person just looks at their feet, or gives me something with a texture I like, or spins a pinwheel. Deep pressure is another things that helps. I think that may be part of why I had a lot fewer tantrums when my (autistic) dad was at home, because he could read me better, and recognizes what's bothering me and how to handle it a lot quicker than anybody else.