Complex sentence: The martologies of Irish Saints coin the expressions "Manchán of Mohill and his companions" and "with allies", both allusions to "his other churches", the locations of which are not recorded, so must be inferred from available evidence.
Split into simpler sentences: The martologies of Irish Saints coin the expressions "Manchán of Mohill and his companions" and "with allies", which are undertood to be allusions to "his other churches". The locations of all "Manchan's churches" are not recorded, so must be inferred from available evidence.