The Polish international, on a season-long loan from Belgian side KRC Genk, was thrust into action during the second half of Rovers' match against Cardiff City, replacing the injured Jake Kean on 53 minutes.
Sandomierski made two key saves in the closing stages of the match at the Cardiff City Stadium, but despite Rovers being on the wrong end of a 3-0 loss, Bowyer was happy with his contribution.
"I thought when he came on he made a couple of great saves," said Bowyer.
"He's a Polish number 3 international so he's not here to make up the numbers that's for sure.
"He's gone on and made his debut in very difficult circumstances."