Every riding training center I was in, a horse that is “light in front” was evaluated and if it was more than the rare little rear, the centers would prohibit anyone riding that horse again and he was gone next day.
One time we received a load of horses from Ireland.
There was in that load a horse that didn’t fit them, looked more like those that came from Hungary or such places.
He was a tall, leggy horse and extremely classy chestnut.
He had beautiful narrow head on a perfectly placed swan neck, lightly built but fleet on his feet like a cheetah.
He felt like riding on a cloud, very responsive and quiet.
I was assigned to him and the few times I rode him, what a treat that was, I fell in love.
He was also very correct jumping the little gymnastics we tried him on.
With a little training, he probably was going to make a really handy, very competitive jumper.
There was a little problem, no matter how careful I was not to go there, about once or twice a ride, no reason we could see why, he would be going fine, then rear.
That was not a levade sitting on his hocks but a straight legged rear, as high as he could reach with his front feet and waving them around.
It was almost like a trick, as if he was trying to clap up there.
It never felt like he was unbalanced or maybe going over, just got very high up there for a few seconds, then back to work like nothing had happened.
Still, that scared all watching, it looked so dangerous.
The director was notified, he came see for himself, had me get off and horse was gone next day.
Very young me was really sad, but maybe the owner had been warned that may happen and decided it was that bad and he was not suitable for retraining and selling, too dangerous if he repeated that catching someone off guard and someone could be hurt.
Years later, I had a good trainer friend killed when a new horse reared and fell on him.
That the OP’s horse is “light in front”, that I would take seriously.
Depending on what that means, consider seriously if that is a suitable prospect that will be able to re-sell with a clear conscience no one may be hurt by that, plus the danger to the one retraining.
Other than that, if the horse seems to be what the OP likes and affordable, why not?