This is incidental. These trials just happened to end up in the Hildibrand Adventure quests, but would have the same problems regardless of what questline they'd be attached to.
The last two trials that showed up in the Manderville quests were both featured at Fan Festivals. As such, they are made for when the first Fanfest rolls around, but are included in the game only after the final one is over.
This has a few consequences:
- The boss will be designed to be completed by groups of people randomly assembled at Fanfest within a time limit. Square still wants the majority of people there to be able to beat it, so the mechanics are severely undertuned as a result.
- The boss will be tuned to the iLevel that was "current" when the first Fanfest occured, but released a good 2-3 patches later. This means pretty much everyone will be overgeared for it, further reducing the challenge.
- There is no EX version as the trials are made for Fanfest only. As such the usual rewards for those are not provided.
The first two points are likely to never change with Fanfest battles, as Square wants to build the trial and then not worry about it anymore, re-tuning it every Fanfest and then again when it releases into the game.
The last one would require Square to allocate resources that they are apparently unwilling to commit to it so far, and it may be the one thing I could see them change one day. I would be very much in favour of Fanfest battles getting an EX version, which could then be tuned to the time they release in game, as that version wouldn't be at Fanfest. Alas, I won't hold my breath for it.