Couplings are a safety issue on brake lines. No safety issue on the hydralic suspension. Even just good compression fittings might get by on them.
The unit pressure is very high but the cross sectional area is very small. I very much doubt that there is more than 100lbs effective pressure to separate the coupling with such a small line internal cross section.
I guess I could do the calculations to be exact. The line pressure is say 1500 lbs per square inch. You are dealing with an area much smaller than 1/15 of a square inch.