If the activation of a Glyph of Warding triggers additional Glyphs of Warding, who is the target of the additional spell glyphs

Yes you can cast spells that target self into the glyph

Spells that target "self" meet all the criteria for allowed spells

Glyph of Warding describes all the limitations for which spells can be stored in it:

You can store a prepared spell of 3rd level or lower in the glyph by casting it as part of creating the glyph. The spell must target a single creature or an area.

There are no other limitations.

Since spells that target "self" only target a single creature explicitly they meet the single-target criteria.

Targeting - specific beats general

One might wonder how a "self" spell would be targeted upon the glyph being triggered, but the spell covers that as well:

If the spell has a target, it targets the creature that triggered the glyph.

Does a spell that targets self have a target? Yes. So, according to the spell that self spell will now target the creature that triggered the glyph.

Specific beats general. So this supersedes the restriction that self spells only be able to target the caster.

In order for this spell to function as designed, it necessarily supersedes the normal targeting rules for spells with its description.

It's worth noting that this spell also necessarily supersedes several other major general rules (Spellcasting effects, concentration) with its specific effects in order for it to function.

Thus, there is absolutely no reason why this isn't fully allowed.

The spell's wording has changed

It is worth noting that an older version of the spell description began with the line:

When you cast this spell, you inscribe a glyph that harms other creatures.

However, the spell has been the subject of errata, and the first line now says:

When you cast this spell, you inscribe a glyph that later unleashes a magical effect.

This appears to be a confusion point.

A stored spell (probably) has the same range as the normal version of that spell

There is nothing in Glyph of Warding's text that explicitly states a maximum or minimum range at which it can cast a spell. The Range for Glyph of Warding itself is "Touch", but that is presumably to create the Glyph, not for effects the Glyph creates. The Glyph itself can "cover an area up to 10 feet in diameter", but that does not necessarily mean its effects are limited to this area.

There is a small hint in the text that the Glyph can effect things which are not touching it. Specifically, amongst the possible triggers it states (PHB, p. 245 bold added)

typical triggers include touching or standing on the glyph, removing another object covering the glyph, [or] approaching within a certain distance of the glyph.

However, this does not tell us definitively whether or not the Spell Glyph can cause effects at any particular range. After all, the the Explosive Runes version of Glyph of Warding effects things in a 20 foot radius sphere centered on the Glyph, so a trigger of "when a creature comes within 15 feet of the Glyph" would be a reasonable (if often sub-optimal) trigger for that feature alone.

The biggest hint we have is simply the description of what happens when a Spell Glyph is triggered (PHB, p. 246, bold added):

The spell being stored has no immediate effect when cast in this way. When the glyph is triggered, the stored spell is cast. If the spell has a target, it targets the creature that triggered the glyph.

The triggering of the glyph will cast the spell you stored in it, in your case Greater Restoration. The spell will have all the qualities that it usually does, including range, duration, and effects.¹

If Glyph of Warding changed features of the spells it "casts", its text would say so. Since it does not, the Range of the stored spell most likely remains unchanged. So a creature would need to be touching the Glyph of Warding in order to benefit from a stored spell of Greater Restoration, since Greater Restoration's range is Touch. If the stored spell had a longer range, that range would be used instead. For example, if you stored the spell Haste into a Glyph of Warding, the Glyph could target any creature that triggered it with a Haste spell as long as that creature was within 30 feet of the Glyph (the range of Haste being 30 feet).

_{1: The only feature of the spell we can be sure will change when it is triggered (besides "concentration") is its components: the components are necessary for "casting" the spell (so you presumably needed them when you "cast the spell" as part of the casting of Glyph of Warding), but we are already told that "the stored spell is cast" when the glyph is triggered without any caveats (which is good, since the Glyph has no hands to gesture somatically or mouth to speak the verbal components). So the components will be unnecessary when the spell is triggered, the same way it would be unnecessary to pay gold for an item that a spell magically created, even though that item usually costs gold at a store.}