As an ultra distance athlete doing events of 500 miles and greater. I see the Triathlete is suggested, is this correct? Will this choice also have sufficient intensity to increase FTP?
My concern is the comment in the description which states Riders recovering from injury can also choose the Triathlete as it maintains an easy pace during work outs.
If you want some high intensity you’ll need to choose a shorter focus duration. Eg climber or GC specialist
You can increase threshold from the bottom via low intensity (and would suggest that’s still the bulk of training - aim should be a very high training load too), but at times it’s good to raise the ceiling with some high intensity, and most coaches would prescribe some.
Similar question has come up before eg here, and here and you can search the forum for others… but that’s the gist of it 
As an aside, if you’re v new to Xert, they have a series of videos as well as podcasts which give more tips for getting the most out if it
I’m going for the Super Randonneur audax award. After much thinking ,which hurt my tiny mind, I’ve decided to go with GC Contender to get a more rounded type of fitness so I can get over hills and battle headwinds. I’ve worked out roughly what the XSS demands are likely to be for my big rides and I’m aiming to get my training load to roughly 1/4 to 1/3 of that before I do the longer rides. I’ve set my improvement rate to build at a constant steady rate rather than going down the more aggressive IR with rest weeks.
I chose to use a Target Event Date rather than Continuous Improvement, so at the moment I’m in Pre-Base which is working sort of like Continuous Improvement in that it recommends harder workouts when I’m fresh and endurance when I’m tired, then at the end of this month it will automatically switch to base, so far this is all working out quite well. I inputted some power values into the PD Curve generator and then put those into an activity before I started training again properly, as the activities that Strava had sent previously had given me a slightly wonky fitness signature. I’ve since switched to recording my indoor activities on the Xert EBC app and outdoors on my Garmin (and uploading from Garmin not Strava) and my Fitness Signature seems to be tracking how I feel much better than in the past when I uploaded from Zwift/Strava.
Hope that helps, would be good to have an Athlete Type for these sort of events , especially as they seem to be growing in popularity. Would make my brain hurt less if nothing else!