The mem-vav after the word Avrech (which means a young married man), which does likely represent the word "Moreinu", would be either an honorific, or would indicate that he was a teacher.
Although the "Rabbani" before his father's name does mean a "learned scholar", there is an additional abbreviation here: mem-vav-hey. This stands for "Moreina haRav", and translates to "our teacher, the rabbi".
Thus, his father was definitely a rabbi.
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