From: Rabbi Moshe Sofer
To: Unknown recipient
R. Ephraim Zalman Margolios ruled that prayer in an invented or corrupted language is categorically invalid; the Chasam Sofer disagrees, holding that any dignified language used in royal courts is valid for prayer, analogous to the requirement of dignified dress during prayer. Nevertheless, both agree that Jews should pray exclusively in Lashon HaKodesh, recognizing the Reformers' intent to erase Hebrew and the memory of Jerusalem.
Source: Shu"t Chasam Sofer CM §193