"We run around the hall."
Translation:Rithimid timpeall an halla.
No, ritheann muid thart ar an halla should not be accepted. However, "ritheann muid timpeall an halla" is accepted.
I'm open to correction on this, but I think that rithimid timpeall an halla means "we run (a)round (the outside) of the hall", whereas rithimid thart ar an halla means "we run (a)round (inside) the hall*.
I'm not sure that I would differentiate between round and around in these sentences. For me, the given sentence doesn't strongly imply either one of the possible meanings.