Your interpretation is probably correct, but I would not condemn them for that as many do. If someone is truely seeking God, good for them. All Christians will make mistakes along the way. Accepting Jesus, seeking God and loving one another are the most important concepts, IMHO.
I will agree that they are most likely sincere, but they are also sincerely wrong and teaching a false doctrine as truth.
THAT is the problem of the ages, WHAT DID GOD SAY?
Eve twisted it, Adam ignored it, Noah listened to it, Abraham doubted it...and so on.
The most consistent doctrine taught in the Bible is to do what God said, and to not add to it or subtract from it.
Telling people that tongues are a valid gift for today and that tongues are a sign for BELIEVERS TODAY is a direct contradiction with what the Bible teaches, and therefore, sin.