I can verify that switching to the JAR launcher works. Once I loaded the JAR launcher it was set to 1.13, I changed it to Forge, which failed, but upon closing and relaunching from the Twitch app, it came up with FTB Revelation profile. I think the first time you switch to the JAR launcher, and it gives you the message about resetting your profile, and makes you supply your login credentials, this gets in the way of the Twitch app feeding the necessary info to the JAR launcher, so just login, then close it, and relaunch from the Twitch app and it should carry the correct profile over.
I also had an issue with the JAR not supporting the expansion of memory, as I have the memory expanded to max (like 12G though it seems to cap at 10G), because of using the 32-bit java. If you go back into the Twitch settings for minecraft where you select to use the JAR launcher, there is a drop down to select the correct version of java. change it to the 64-bit java and the flags to expand the memory in the JAR launcher will work properly. If you do not have the 64-bit version of java installed, you will need to go download the 64-bit version, then go back into Twitch app settings and select the 64-bit version, etc.
After all of that, I was able to launch FTB Revelations via the JAR launcher, and seems to be working properly.
\o/ Cheers!