"Os bydd Gareth yn adolygu bydd Megan yn hapus."

Translation: If Gareth will be revising Megan will be happy.

[PolMicheal]

Why is the first part of the English translation in present tense?

[EllisVaughan]

Because that's how you'd say it in English. Directly translated the Welsh is "If Greath will revise Megan will be happy." which doesn't make sense in English.

[PolMicheal]

Do "if" statments always use future tense in Welsh?

[ibisc]

Not always, but they tend to, on the basis that if it isn't happening right now - in which case there would be no 'if' - then any uncertainty is in the future.

[Deyan161]

"If Gareth will be revising" is not present tense but future continuous and, as a native English speaker, surely this is an incorrect translation - unless it's used in the USA. I would say either "If Gareth revises..." or (possibly) "If Gareth'll revise=will revise". "will be revising" signals to me an L2 speaker.

[ibisc]

This is a zombie sentence, so we may not still be able to get at it to correct it. We are still waiting on Duolingo for a fix for the zombie sentence plague.