It's... subjective though, I'm saying that's how confident I am, not that there was 99% chance that they didn't fight. We literally have no idea what happened, but if anything happened, BIg Mom would say so or give indication. I don't remember what Oda mentioned about Kidd on WCI, other than him beating a commander?99% is very bold.
If we go back to WCI, we were told Kid went to WCI and got chased out which was true. By that, we would also say 99%, Kid didn't fight anyone.
Although when we came to Wano, we were told while he did get chased out of WCI, he did injure a commander, so yes, Roger did leave WCI, but we can't say he definitely didn't fight with Big Mom.
Even Luffy who came to just save Sanji and the Vinsmokes still ended up clashing with Big Mom, so, it's quite possible they did fight and Roger was able to successfully take her down,
On top of that, Big Mom knew Roger used VOAT to read the Poneglyph which may suggest she witnessed Roger do it, so at the very least, there must have been an encounter.
On a different note, Roger's reputation must have been so bad if King thought the closest thing to JoyBoy was Kaido of all people, the warmonger. Then again, only few people knew Roger was a good person.
Luffy wanted to fight Big Mom, and every decision he made was going to bring him to clash with her, after she knew he was on the island. We don't know what happened with Roger, other than her knowing he invaded her territory and used Voice of All Things.
