Unfortunately things haven't been looking great on Rudy's chances. She's certianly somewhat of a "problem" female in that she's been very cautious or unreceptive around any new bulls she's placed with. It took her a long while to warm up to Sabu, who she did end up breeding with but evidently didn't take. Her and Johnson didn't really hit it off either with her being terrified of him and him chasing her down, far from the ideal scenario for her ticking clock. And afaik they haven't been housed together consistently or at since, which would make sense given they've been largely keeping Johnson on his own due to 2/3 females being pregnant and him not being "needed" outside of with Rudy. Perhaps these circumstances have changed since, but I haven't seen much to indicate otherwise.
I'm not sure if Johnson's behavior was strictly with Rudy or if it extended to the other elephants (though I'm inclined to say that it was moreso with her since I did see pictures of him interacting with Frankie seemingly without issue), but it's definitely not the best circumstances. Perhaps Raja may be the better bull for the job, if it isn't too late already.