I’ll ask the question again: when the Portugese paper states that the JP were investigating a link between the sex attacks on the Algarve and Madeleine’s disappearance do you think they completely made it up?
This story arose because OG turned it's attention to this line of enquiry. The UK media took the opportunity to criticise the PJ (again) for not telling OG about it earlier;
Wednesday 19th March 2014
Redwood appeals for information about the man who allegedly attacked children in the Algarve. A burgandly top was mentioned. It was said that there were 12 incidents, nine of which were reported to the Portuguese police. UK news said that the Portuguese police didn't pass on the information about these crimes to OG; they only found out about it when three families responded to an appeal for information in 2013.
https://www.channel4.com/news/madeleine-mccann-police-appeal-sex-attackerWell that's wrong for a start. Kate McCann wrote about it in her book in 2011. She said she found the information in some files. However;
The Portuguese have been accused once more of incompetence, so anything they say is going to be defensive. Amongst other things, they said that OG was told about it in October 2013 by the PJ, but OG decloned to comment;
Contacted by PÚBLICO, one of the spokesmen of the Metropolitan Police of London declined to comment on the clarifications made by the PJ, refusing to confirm or deny that British investigators were informed months ago by the Portuguese about this line of investigation. It remains to be explained why Scotland Yard decided to announce on Wednesday that it is looking for a sex offender.
https://www.publico.pt/2014/03/19/sociedade/noticia/pj-reabriu-inquerito-maddie-ha-meses-por-causa-de-suspeito-procurado-agora-pelos-ingleses-1628961In my opinion it's by no means clear where the information came from or who knew about it and when. There were rumours but nothing concrete was said by any identifiable source.