Do Galactus' Herald and Master Mold's Sentinels need to be modern age to be used in a modern age Tournament?

Modern Age can only be modern age; so yes.

That would seems the way it should work but without it being specified It leaves it open for interpretation. I'm really hoping for a full article like the one larfleeze got to clear up all these issues with galactus which will set precedent for mastermold.

Just like sealed games treat what you pulled as the only things in the game, so does Modern Age treat only modern figures as being in the game.

And for a ruling on a power with a similar intent, you can look at Fixer's Final Word in regard to "Cobble Any Object Into a Weapon".

And don't forget, just like alcohol, you need to be 21 or over to be able to use Sentinels and Heralds!

Kidding. But the thread title just asked for that kind of joke.

It doesn't need to be specified in the traits. A Modern Age game is Modern Age. Golden Age is Golden Age.