Okay, I'm just going to post all of my current suggestions here.
J-Dog is the one saying these lines on No. 5 - "Like, oh my God, is that Charlie Scene?", "That's hot!", "Dude, is it true that you screwed my mom?", and "Check, please!"
Da Kurlzz is on Young. I don't know how much I can stress this. During the third verse where both Deuce and Johnny sing "We will fight...or we will fall," there is a short pause between the two phrases each time they say it. At first, you hear a soft voice in the background saying "We will fight" and "We will fall," but as the verse progresses you hear this voice start shouting "We will fight!" and "We will fall!" and it sounds just like Da Kurlzz. The wiki has it right now as Deuce but that sounds nothing like his shouting voice.
Da Kurlzz is on Shout at the Devil. He has one solo line in the song, which is "What's up, bitch?" at the end of the second verse. He also joins in with the other members on some lines in the third verse, such as "And then he'll have you crying for more," "He'll put the thrill back in bed," "But in the seasons of wither we'll stand and deliver, be strong and laugh..."
Da Kurlzz is on Glory. During the third verse, there's someone screaming behind Danny and J-Dog. Sounds like Kurlzz, and right now the wiki does not credit this screamer at all.
Da Kurlzz is the one shouting "Hut One! Hut Two! Hut Three! Go!" on Pigskin. This will probably get shot down, but I still want to express my opinion.
Da Kurlzz is the one singing the intro/outro of Dark Places. The band said it was him, it sounds like him, I think it is him.
On Does Everybody in the World Have to Die, there are three lines ("Pray...", "Pray...", and "Now!") that are in the lyrics but don't have the right people credited for saying them. Now I'm not gonna say this is Da Kurlzz, but the person saying "Pray..." sounds nothing like Johnny, and the person screaming "Now!" could be J-Dog but it sounds nothing like the rest of his screams in this song.
Oh, here's my favorite one to argue with people about. Da Kurlzz is the one shouting "Oh, gravity!" on Gravity. Well, at least he's a part of the line. I do admit I hear Danny here, but Da Kurlzz is there too, also evidenced by the music video. Why wouldn't he be here? If Da Kurlzz is saying this line, that means that every member got at least one part on the song, which would fit the theme of the track.
The voice whispering "This is how we roll..." at the end of How We Roll is Da Kurlzz. The scratchiness is there and everything.
The bridge on Save Me is done by Funny and Danny, not Charlie and Danny. Before the bridge begins, you can hear Funny's infamous "haha" breath before he starts singing, this is most noticable at the end of the first verse. Someone pointed this out on the HU Reddit, but I've thought this was Funny before that got posted. Funny is also credited as a writer on this song, while Charlie isn't.
This was also pointed out by the mod on Reddit. The person singing "Take me hoooome!" at the end of the first two verses on Take Me Home is Charlie, not Danny. You can hear it in the voice. I also believe that Danny isn't backing up Charlie on the chorus, that's Charlie backing himself up similar to how Johnny did on Ghost's third verse.
Okay, well there's everything. I know most of these will be rejected for various reasons, but I hope you take them into consideration.