Is dyslexia regarded as a severe disability for academic applications?
Dyslexia is widely recognized as a disability.
Deciding if dyslexia is &quot;severe&quot; is a matter of opinion.  Only one person has a well-informed opinion about the severity of your dyslexia: you.  If you think it is severe, no reasonable person will question it.
Your strategy of mentioning your disability in the context of how you were successful overcoming it is a good strategy.