They do not speak commonCommon. It would have ramifications on a plotline.
See their Stat Block:
Languages: Giant
You would currently break the methods that solve the encounter by providing a solution that
reveals intentions of the Frost Giants if the Winter Wolves aren't present (because you tried to separate the Giants from the Wolves or similar approaches).
The ramifications of this are that you would not be able to
gather information about the Ring of the winterWinter that the giants seek.
Choosing to grant the creatures the Common language may quickly solve the aspect of an ambush by a murder-hobo party or similar threats which would result in
a combat encounter instead of a social encounter.
On the behaviour and interaction, see ToA page 64-65:
of combat or social encounter.
This doesn't break the entire campaign, but the encounter as written and changes the option for your players. Perhaps even limiting their agency if poorly played out.