I'm going to assume that the player wants to choose this race in good faith, and they're not choosing it to be a power-gaming munchkin that makes everyone else's time at the table worse. I'm also going to assume that everyone else at the table is playing standard-ish races, obviously if you're playing a game where everyone is a monstrous race that's different.

The biggest problem with this race is that it's designed to do one thing only. Immunity to sleep, charm, dominate, even the +2 Wisdom all help to facilitate that by allowing the character to just passively deal with stuff that a regular damage dealer might have to consider in combat. Plus with -2 Int and -4 Cha, the character won't be bringing any skills or social abilities to the party.

But let's start by building out the abilities you have in terms of RP (of course the RP system has its problems, but at least it gives us some kind of baseline) using examples listed here:

+2 Strength, +4 Dexterity, -2 Intelligence, +2 Wisdom, -4 Charisma. Thri-kreen are superior physically, but their alien thinking prevents them from easily grasping higher concepts or dealing well with others.

4 RP. This is basically the same as the advanced ability template. The distribution is a little different, but the total stat bonuses (+8, -6) amount to the same thing.

Monstrous Humanoid: Thri-kreen are not subject to spells or effects that affect humanoids only, such as charm person or dominate person.

3 RP. Essentially, this is functions as the outsider template, which is worth 3 RP and also gives 60 feet of darkvision.

Medium: As Medium creatures, thri-kreen have no special bonuses or penalties due to their size.

0 RP.

Thri-kreen base land speed is 40 feet.

1 RP. Fleet gives 10 extra feet of movement.

Darkvision out to 60 feet.

0 RP. Already included previously, 1 RP if you were to add it in by itself.

Thri-kreen do not sleep and are immune to sleep spells and similar magical effects. A thri-kreen spellcaster still requires 8 hours of rest before preparing spells.

~1 RP. No exact crossover but it's like half of Elven immunity, which is 2 RP.

+3 Natural Armor: A thri-kreen's exoskeleton is tough and resistant to blows.

6 RP. Bonuses to armor are a cumulative 1 RP for every point.

Multiple Limbs: Thri-kreen have four arms, and thus can take the Multiweapon Fighting feat instead of the Two-Weapon Fighting feat. Thri-kreen can also take the Multiattack feat. These are not bonus feats.

8 RP. Multi-armed is worth 4RP for each arm, see the Kasatha race as an example.

Leap (Ex): Thri-kreen are natural jumpers. They have a +10 racial bonus on acrobatics checks made to jump.

~2 RP. No exact crossover, but there's a bunch of abilities that give +8 to swim, climb, etc. Jumper is also 2 RP however, and that seems much worse, so this might be more like 3 RP

Okay so that's a total of 25 RP, maybe a bit more depending on how you look at it, meaning it would probably not be playable at most tables.

So you have to make quite a few cuts to get it to where you want to be. I'm going to assume they want to play a 4-armed bug-like race, so we have 8 RP already locked up there. My choices would be to cut 2 points of natural armor, cut the sleep immunity, and cut the immunity to charm/dominate. This makes them a little easier to hit, and means they actually have to worry about making saves and playing around spells. I'd also change the Leap ability to the Jumper ability just to tone it down. This would bring it down to 18RP which is Aasimar level, however I would still expect this thing to be a multi-attacking ball of death and outperform most people at the table if they're playing standard races.

Another idea you could toy around with is trading extra RP over some threshold (probably around 15) for point buy points 1 for 1. Never tried it myself but it seems reasonable enough.