Anwar and Saiful can be seen together at the condo or any hotel room but mere physical presence does not prove sexual act took place. Anyhow Anwar said he can produce an alibi during the alleged date and time.
Finding Anwar's stains on the mattress prove that some sexual activity has taken place at some time there but does not prove that the allegation happened. Anwar can probably say it was 'DIY'. It’s just circumstantial evidence which will not be enough to convince the judge beyond reasonable doubt.
The only way to prove the case beyond reasonable doubt is to find Anwar's semen DNA in Saiful’s violated backside.