Studies have been ongoing since 2016 into whether the rare snails, that measure just 0.2in (5mm) across, would survive being relocated.
The latest report says those snails that have been moved have become strong breeding populations; recovering and expanding their initial low numbers.
Snails were taken from ditches at Acle using a 0.5mm mesh net.
They were moved to new homes at Shipmeadow Marshes, Beccles Marshes and Sutton Fen, all in Suffolk and Norfolk.
Numbers increased drastically at Beccles Marshes – according to the report – and evidence suggests there is a small but growing population in Sutton Fen, an area that never previously supported the species.
None of the snails have been detected at Shipmeadow.