sent > sent, hence: transmuted; also: sended (used of a ship pitching deeply with head or stern in the trough of a wave)
5 And otherwhere the snowy substance sprent
otherwhere > elsewhere sprent > sprinkled (pa. ppl. of "sprenge")
6 With vermeil, like the boy's blood therein shed,
vermeil > scarlet the boy > (See note on Jason and Medea at 212.44:4)
7 A piteous spectacle did represent,
represent > bring to mind; make manifest; symbolize
8 And otherwhiles with gold besprinkled:
otherwhiles > at other times; now and then (the original pointing also suggests: "And otherwhiles, with gold besprinkled, It seemed the enchanted flame …") besprinkled > {Sprinkled all over; the prefix is intensive}
9 It seemed the enchanted flame which did Cre{u"}sa wed.