This requires removal of ALL linen fibers. This takes an extra 45 - 60 minutes. You will be given a verified non-linen stiffener. You then have to take the suit to a tailor for restoration. Collar stiffener, button threads, inside canvas, waistband, and other places.
Many manufacturers use material from many suppliers.
Two suits with the same brand may be made in different factories, sometimes in different countries. The kosher status of one does not reflect on any other.