SS will certainly be involved and I would imagine he would not be allowed to return to the family home if children are present, though perhaps it would be different if they are his own children. If you haven't watched it, I would watch Married to a Paedophile (I think it's on iplayer?). One of the men was not allowed to move back to his home if his wife was to still have their grandchildren visiting there, so he had to move into a flat nearby. But often it is the case that even on a Sexual Harm Prevention Order (which he will be on), it is possible to have contact with children with parent's permission.
I have a family member who served time in prison for sexually abusing a child in the family. He was allowed to have contact with any children, including in his own home, without the parents needing to be notified, with the exception of overnights. If a child was to stay overnight in the home, they had to be interviewed by the police/probation officer/SS (I can't actually remember now) so that they could be notified of his convictions in order to decide if they were comfortable with their children having overnight contact. I know because we were the parents and we had to be told this and asked to go to the police for our interview so that our dd could stay over (!!). Dh and I had no idea. We are now NC and have never seen him again.
So that is to say that the restrictions he is placed under could be quite varying and may not be entirely sensical, particularly given the risk of abuse even with other people in the room. But very likely, his partner does know the extent of what he is convicted of doing. It's just very likely she has chosen, for her own self preservation, to put her head in the sand and live as if it's not true. This could very well be the case with other family members too or who have perhaps only been told half the story by the partner.
Of the two people I know who are married to men who were convicted of sexually abusing a child, both of their partners are still with them. In one case, the child abused was his own child. The families have created entire narratives to explain how it happened and how it wasn't really a big deal. They've told such elaborate stories about the children involved now and how their partners ended up in a situation where they abused a child that even they don't remember what is truth and what is fiction. They're very happy living in their small little worlds, even though they have lost friends and family as a result. I don't think you'll be able to convince people to change what they think.
But if you do know of any children who are having contact with them who don't know, then I would find a way to get the links to those news articles to them. In our case, my dc had contact with these people for years when everyone around us knew and no one ever had the courage to tell us (thankfully, I have no reason to believe my dc were ever harmed). There was even a family meeting to discuss how to keep it quiet so we wouldn't stop contact. I would have appreciated so much if someone had cared enough about us to speak out.