well, as long as her 1/2 on or round off do not go in the direction of that I-beam, then she'll probably be okay.
the vault table is approx. 3 feet wide. so, from center you have 1 1/2 feet of table, and 3 feet away from the I-beam as you stated. this equals approx. 4 1/2 from the center of the table to the I-beam.
if she doesn't turn in that direction she'll be fine. if she does? probably not a good idea if that I-beam and wall are not padded. and does the landing mat go up to the wall?