SCAG tiefling variants should be replacements for standard tiefling abilities.

Charactermancer and Compendium are not handling the SCAG tiefling subrace as RAW. SCAG tiefling variant as RAW should be replacements for specific abilities. Feral should just replace the +1 int and +2 cha with +1 int and +2 dex. Thaumaturgy et al should be still added. Devil's tongue should just replace Thaumaturgy et al with viscious mocking. The ability score modifiers should be the same as the PHB modifiers. The above should be the same for the other 2 subraces. PHB Tiefling Traits Tieflings share certain racial Traits as a result of their infernal⁠ descent. Ability Score Increase. Your Intelligence score increases by 1, and your Charisma score increases by 2. Age. Tieflings mature at the same rate as Humans but live a few years longer. Size. Tieflings are about the same size and build as Humans. Your size is Medium. Speed. Your base walking speed is 30 feet. Darkvision. Thanks to your infernal⁠ heritage, you have superior vision in dark and dim Conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkn⁠ess as if it were dim light. You can’t discern color in darkness⁠, only Shades of Gray. Hellish Resistance⁠. You have Resistance to fire damage. Infernal⁠ Legacy. You know the Thaumaturgy cantrip. When you reach 3rd Level, you can cast the Hellish Rebuke spell as a 2nd-level spell once with this trait and regain the ability to do so when you finish a Long Rest. When you reach 5th Level, you can cast the Darkness spell once with this trait and regain the ability to do so when you finish a Long Rest. Charisma is your Spellcasting ability for these Spells. Languages. You can speak, read, and write Common and Infernal. Feral Tiefling Traits Tieflings share certain racial Traits as a result of their infernal⁠ descent. Ability Score Increase. Your Intelligence score increases by 1, and your Dexterity score increases by 2. Age. Tieflings mature at the same rate as Humans but live a few years longer. Size. Tieflings are about the same size and build as Humans. Your size is Medium. Speed. Your base walking speed is 30 feet. Darkvision. Thanks to your infernal⁠ heritage, you have superior vision in dark and dim Conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkn⁠ess as if it were dim light. You can’t discern color in darkness⁠, only Shades of Gray. Hellish Resistance⁠. You have Resistance to fire damage. Infernal⁠ Legacy. You know the Thaumaturgy cantrip. When you reach 3rd Level, you can cast the Hellish Rebuke spell as a 2nd-level spell once with this trait and regain the ability to do so when you finish a Long Rest. When you reach 5th Level, you can cast the Darkness spell once with this trait and regain the ability to do so when you finish a Long Rest. Charisma is your Spellcasting ability for these Spells. Languages. You can speak, read, and write Common and Infernal. Devil's Tongue Tiefling Traits Tieflings share certain racial Traits as a result of their infernal⁠ descent. Ability Score Increase. Your Intelligence score increases by 1, and your Charisma score increases by 2. Age. Tieflings mature at the same rate as Humans but live a few years longer. Size. Tieflings are about the same size and build as Humans. Your size is Medium. Speed. Your base walking speed is 30 feet. Darkvision. Thanks to your infernal⁠ heritage, you have superior vision in dark and dim Conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkn⁠ess as if it were dim light. You can’t discern color in darkness⁠, only Shades of Gray. Hellish Resistance⁠. You have Resistance to fire damage. Devil’s Tongue. You know the Vicious mockery cantrip. When you reach 3rd Level, you can cast the Charm Person spell as a 2nd-level spell once with this trait. When you reach 5th Level, you can cast the Enthrall spell once with this trait. You must finish a Long Rest to cast these Spells once again with this trait. Charisma is your Spellcasting ability for them. Languages. You can speak, read, and write Common and Infernal. Those are 2 examples of how the subraces should be.

Hi Woof! If you want to see Roll20 fix issues like this, the best thing to do is to put all that gathered information into a  Help Center Request . That will create a ticket for eventual correction in the Compendium. A report on the forum has a hit-or-miss chance of official recognition, and can't be tracked. 

I did create a help desk ticket and it was ignored and closed.  Thought I would shame them maybe.

Hmm. "Ignored and closed" doesn't sound right. As it has been explained to me in the past, if it is a problem that the XP team can't solve (they are not the dev team) they will pass it on to the dev team bug list. Since XP can't really do anything further, it can look closed to the end user. I've complained about this in the past, since it's frustrating for the end user. However, once filed, the bug report does go into a dev investigation ticket. There's just an annoying disconnect between user and the actual process. Rest assured that if you have filed the issue, and it has been responded to, someone, somewhere is given the task of investigation.