They only have 3 RBD's for PE, while they have 5 for J and >10 for Y, making PE the hardest to differentiate, basically they're limited to low flex/mid flex/high flex with appropriate discount levels.
On the domestic market, they use differentials to prevent these shenanigans from happening, with premium cabin fares requiring dual inventory to prevent lowest F from ever being cheaper than lowest Y. However, INTL has 3 cabins, so to make sure lowest J is always higher than lowest PE which is always higher than lowest Y, they would need triple inventory fares for J, and I'm not sure that 1) I've ever seen that before 2) that is actually possible 3) this would go well on the INTL market and wouldn't create havoc when mapped to domestic or partner flights.
Wouldn't branded fares offer a solution to this problem? How is LH handling this?