If pro se litigants send letters to the court, what happens next will depend upon the practices of the court and judge. Some judges will send copies to the other party. Some will drop them unread into an envelope and raise the issue at the next hearing. With some, being as they are not being properly filed, they may be returned to sender or dropped in the trash.

It's not possible to evaluate whether or not the conduct is sanctionable based upon the information we have been provided so far.