This is a little too powerful

When it comes to 5th edition tactics, spreading the role of Concentration around is very effective as it allows the high Constitution characters to concentrate on their own enhancement spells like enhance ability, haste, or polymorph. This also opens up the spellcaster's Concentration for other spells (usually less tactically important ones such as entangle or cloud of daggers).

Your feat makes accomplishing this virtually trivial. You simply pack a rune with the enhancement spell for 20 gp (a relatively small amount) and the fighter/barbarian/paladin has its own Concentration spell. This is even more powerful than spell scrolls (which linkassin's answer tackles the relative monetary and time costs of) since the character need not even possess the correct spell list to gain access to the spell.

Stockpiling

This also allows the stockpiling of runes for a dangerous dungeon throwing out encounter balance. Scribing spell scrolls takes significant downtime, but a spellcaster could convert their entire set of spell slots into runes in a day at lower levels. This means that they have a full set of additional spells to use for whatever difficult challenge presented itself.

Wording

There are a few instances in your homebrew where the wording doesn't quite align with the styles that Wizards of the Coast seems to adhere to. Here is a revision I put together in an attempt to remedy this. It is by no means 100% supported, but based on observations I've made in reading through the books (probably too many times):

Rune Caster

Prerequisite: the ability to cast at least one spell of 1st level or higher

You've developed the skills necessary to set your spells in runes to hold their magic for a later time. To do this you cast a spell as normal but the casting time is increased by 1 hour, you must expend additional material components related to the type of scribing costing 20 gp per spell level, and the spell has no effect other than creating the rune. The object you are scribing the rune onto must remain within reach for the entire casting time.

While scribing the rune, you choose a trigger condition that activates the rune. This trigger condition must involve either a command word or a touch, and can include both. You can further refine the trigger to require certain characteristics such as by requiring a specific creature or creatures, or the use of certain body parts. The set of creatures or body parts that are required can be as broad or specific as you like.

When a creature activates the rune, the creature casts the spell as normal except that a spell with a range of Touch becomes a spell with a range of Self. If the spell has an area of effect, the origin of the area of effect is the rune. Once the rune is activated, it disappears, leaving no trace of its presence.

Note that I removed the wording about choosing targets since it is redundant as the creature casting the spell always chooses the targets. Additionally, the section on having the GM interpret the trigger "as the character would" is largely confusing and if the GM is actively trying to use wording to adjust the usefulness of the feat, there are probably other problems at the table. The rest of the changes are mostly to allow it to read in plain English with some small word-choice decisions based on other similar examples in the official content.

This spell should probably be 3rd level, not 2nd level

The issue right now is that as-written, this spell is strictly better than the Darkvision spell in every respect except for its range and duration, which is not consequential enough to keep the spell as a 2nd level spell.

It's not quite as powerful as a 6th level spell, though, like Truesight, which has a longer range and detects lots of other things than just allowing vision in darkness. So that puts a firm upper bound on the power level this spell should target.

Pros:

• Allows normal Perception checks in pure Darkness
• Has no Material Component (can be cast without a focus)

Cons:

• Lower Range (normal Darkvision has a range of 60', this has 30')
• Shorter Duration (normal Darkvision has a duration of 8 hours, this lasts 1 hour)

The heightened perception check range is very significant though. Normally, when detecting a hidden creature or object, having disadvantage on Perception would confer a flat -5 penalty to their passive checks, meaning a whole lot of hidden creatures, traps, etc. would be suddenly easy to spot with this spell. Normally, to gain that kind of perception, you'd need to use the regular Darkvision spell and use a torch or some other kind of light effect to at least bring the light level up to Dim. This spell negates the need for any secondary light source, which makes it superior.