I see plenty problems with bellows in general. Happen to design them. If you have in line pressure balanced unit check if it can have any lateral movement and/or flange rotation. No torsion is normally allowed. Axial spring rate can be high. It is sum of the 3 bellows elements. What ever you do with the unit confirm with the bellows supplier or with person who is expert with bellows.

Inline pressure balanced unit will not have pressure trust that is external. All pressure trust forces are internal provided the unit is designed correctly and the manufacturer had correct tooling. I would think most of the time units are a bit out of balance. Forces to consider are spring force, internal friction and unit mass (Plus imbalance if any).

Bellows elements cannot transmit high forces. Material is thin. Typical thicknesses between 0.6 to 2 mm per layer and 1 to 2 layers. Forces are transmitted through the rods. If you have a case where they are under compression they can buckle if not designed for compression.