No, the serious hazard (explosion) is enclosing without venting.Keeping batteries enclosed is strongly suggested. If its flooded batteries, not enclosed is serious hazard.
Be sure your enclosure is freely ventilated to outside.
Leaving them open in the living space is a matter of preference, lots of vehicles put FLA batts under a seat NP.
Some don't mind the smell, or having to occasionally run the fan or crack the window.
But sealed and vented outside is the ideal.