TL;DR Pick which is most important, work towards that goal and be satisfied with whatever happens on the other hand. If raising FTP is your primary goal, make 100% compliance with TR plan and recovery between workouts paramount; if running race is most important, be OK with just maintaining FTP and use the bike as recovery for your running workouts. Trying to do both is likely to end with disappointing results for both.
IME, such a change would be detrimental to building your FTP. Your running is probably also detrimental toward building your FTP and the running probably isn’t helping your Fondo training. The running you have scheduled is likely to cause you to experience inadequate recovery between your hard workouts, and it is likely that your performance in your trainer sessions will suffer because of it. Specifically, your modified weeks would be scheduled as follows:
Hard (bike) -> Moderate (run) -> Hard (bike) -> Hard (run) -> Moderate/long bike -> Moderate/long run
If you want to run, then by all means run. Just be aware that running and its impact on your compliance with the TrainerRoad plans is likely to impair your improvement vs. if you attained 100% compliance with the TR plan, or even raised it up to a MV plan. Your modified plan looks like an awful lot of intensity, though I acknowledge I say that knowing nothing about your background.
Quite simply, training for top performance in a running race while raising your FTP are goals that are at odds. One or the other will probably have to give. So, which is more important? If raising your FTP is, then comply with TR, and reduce running volume and intensity. TR is giving you plenty of cardiovascular intensity that will translate well to your running. Odds are you don’t need as much intensity as you’re programming in your run to do very well.
If the running race is truly important to you, then you need to reduce cycling volume. I would treat the bike as good recovery for the run. You could probably do two easy sessions and one moderate long session in zone 2 and not see much drop off in your FTP, then hit it after your running race and start raising FTP then.
Another option: If you want to mix running and cycling, why not pick an appropriate Triathlon training plan and omit the swims, then shift over to cycling plans after your race?