What does hydrogenated mean here?

The double bonds in the fatty tails have been saturated. It is the same change that turns an oil into a solid fat, and it is done for stability: unhydrogenated lecithin oxidises, darkens and smells.

It can be, and the word on its own does not tell you. It describes the form an ingredient was put into, not how much of it reached your skin.

Is it a barrier repair ingredient?

Not in the way ceramides and cholesterol are. Those are the surface layer's own lipids and phospholipids are not. This one supports a formula's texture and stability, which is a different job.

There is no rating here worth quoting. The numbers circulating for lecithin come from a rabbit-ear assay that transfers poorly to human skin.

The cosmetic material is normally soy or sunflower derived, and the INCI name does not say which plant. A brand that cares about the question will tell you.

Hydrogenated Lecithin — Ingredient Guide

How it works

Lecithin is a mixture of phospholipids, most of it phosphatidylcholine, pressed out of soy or sunflower. A phospholipid has a water-loving head and two oil-loving tails, and that is the arrangement cell membranes are made of: in water the molecules line up tail to tail into a sheet two molecules thick, and a sheet like that will close itself into a sphere.

Hydrogenating it saturates those tails, and two things follow. The unsaturated bonds that made native lecithin darken, smell and go rancid are gone, so the material keeps for as long as a cosmetic needs it to. And straight saturated tails pack together more tightly, giving firmer and more ordered bilayers than the soft ones the native material makes. That is why the hydrogenated grade is the one reached for when the vesicle has to survive.

The evidence

As an emulsifier it is unarguable. It makes fine, stable emulsions at low use levels and gives them a light, sinking-in feel rather than a soapy one. As a liposome former it is the standard choice, and the vesicles are real and can be measured in the beaker.

What the vesicle then achieves is the part to read carefully. Whether it survives the rest of the formula, whether it survives contact with skin, and whether it puts more of anything anywhere it would not otherwise have gone are three separate questions, and a finished product almost never answers them. The ordinary fate of a vesicle meeting the skin surface is to merge into the lipids already sitting there rather than to travel anywhere intact.

One more thing gets conflated. The mortar holding the surface layer together is built from ceramides, cholesterol and free fatty acids. Phosphatidylcholine is not one of them. This is a good emulsifier and a good carrier lipid, which is plenty — it is not a barrier lipid being put back.

Suitability

Suits most skin, and the emulsions it makes tend to be light
Not an active; there is nothing here to seek out
The INCI name does not name the plant it came from, which matters only if you are avoiding a particular one
Circulating comedogenicity ratings for lecithin come from an assay on rabbit ears that reads poorly onto human faces, so no rating is given here

Concentration

No figure. It is used at whatever an emulsion or a vesicle needs, which is set by the oil phase and by the process rather than by skin, and no level of it does anything for you by itself.

Conflicts & combinations

Nothing conflicts with it. The combination that matters is invisible from outside: a vesicle can be broken up by surfactants, by solvents and by the wrong pH, so whether a liposomal product is still liposomal by the time you own it rests on decisions no ingredient list records.