Jefferson Curls and Spinal Flexion Intolerant

My lower back is flexion intolerant. When I do Jefferson Curls or other pike and their variations, my lower back is rounded and if I go further the movement seems to be coming from lower back rather than at the hips.

Will there be any problems by continually lowering myself in Jefferson Curls or should I fix it before attempting this exercise

It's very hard to see people with lower back disorders on flexion. post a side pic of your pike. probably the problem is in the back of the legs.