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They haven't. I'm trying the Infinity fix now, will edit in a bit.
EDIT :: So the file it said I needed (MrTJPCore-1.7.10-1.0.7.14.jar) was not in the Infinity pack. I found it here. If you want instructions on how to make the pack work for the FTB launcher, here goes:
Download the file from the link above, saving it to your downloads folder (or wherever you have it set to save)
In the search box in the start menu, type %appdata% and hit enter. This should open up a file browsing window that displays the files located in the file 'Roaming'.
From there, go to TheLangoliers>minecraft>mods. This folder will have a lot of .jar files in it.
Copy the download from step one into the mods folder. DO NOT UNPACK IT.
Launch FTB and play TheLangoliers. If your only issue was this missing file, it should launch perfectly.