The Front Vault, also known as the "Kong Vault" in Parkour, is one of the more intimidating vaults for most people, but there are ways to work on the technique without the imposed faceplant risks!
Start at ground level to build the mechanics of this movement and then build your way up. When you're ready to use an obstacle, think of vaulting on instead of over it first.
With the proper technique, there's much less of a demand for hip mobility for this skill that first appears. check the video out by clicking the image below:
The biggest misconception people have is that you need to be able to have the mobility to do a deep squat with your hands planted on the ground. In actuality, two factors render this unnecessary:
1) This vault involves jumping into it in a way that your hips raise up. By the time your legs pass over the box, your back is horizontal, and there is a lot more room for your legs to fit through without squatting.
2) Your hands come off of the vaulting surface just before your legs pass them.
Start from the ground and work your way up, and you'll have a firm grasp on this technique in no time. It's not as complex or difficult as it seems at first glance.