Bosch missed the sub-continent tour in Sri-Lanka due to illness a few months ago, and was also absent in the Caribbean recently.
Mashimbyi says the 31-year-old is currently working on her physical strength to be ready for their final series before the tournament in October.
"I've been really happy with her progress, she's practicing fully at the moment, now it's just putting in the work and time and loading up, so that by the time we get to that big camp before we go to Pakistan, she's where she needs to be," said Mashimbyi.
"So far so good, so I'm really happy to have her back in the fold really."
The coach also revealed what work they’ve done in the time since their last competitive match against the West Indies in June, with just a few weeks left until the World Cup.
"Ja, of course, we've been busy at work, we've done some really good ground work with the skills camps and strategic camps we had with the batters, and the national bowling camp as well," he added.
"Now it's about putting in the final touches and getting match ready for Pakistan, where we're obviously going to play three matches and also finalise our combinations within the bowling and batting order."