Jennifer C. Johnson (aka Jennifer Johnson) voiced
Topaz in Sonic X, not
Lindsey Thorndyke, as confirmed by Ms. Johnson herself via email:
This is consistent with the way the cast credits for Sonic X changed throughout the series. Though not exactly episode-specific, names are added and discarded (but mostly added) during sporadic updates (my last check confirms 13 different cast lists). As such, Johnson was added in
Episode 12 alongside Amy Birnbaum (Helen), Kathleen Delaney (Rouge), Andrew Paull (Topaz' commander [known as Cowboy in the original Japanese version]), and Pete Zarustica (Albert Butler) -
one episode after her debut.
Meanwhile, while Rogers does claim the role on
her Facebook profile (under "Photos"), there is proof of her erroneously taking the word of her fans as truth in other instances. One such example:
Madame Muchmoney from Pokemon, who is played by Carol Jacobanis, as confirmed by
the latter's website.
P.S. Johnson's
resume on her official website also states that she was in Pokemon as well. Despite also inquiring about this series, results remain inconclusive as to how she was involved.