They use the word “Ārya” (आर्य) for Suhast Muni ji as a special respectful title.

In Jain tradition:

• “Ārya” means: noble, pure, spiritually elevated person.
• It is used for highly virtuous saints, acharyas and great shravaks/shravikas to show deep respect.
• In many Jain stotras and granths, you will find names like Ārya Mahāgiri, Ārya Rakshita, Ārya Suhasti Suri, etc. Here “Ārya” is an honour-prefix before the name, not part of the name itself. ( jainknowledge.com)

So, Suhast Muni ji is called “Ārya Suhast Muni ji” to show that he is a noble, highly revered saint in the Jain Sangh, possessing great character, discipline and spiritual virtues.