It would be nice to see some more remnants that grow and evolve as you gain levels and can use them more, rather than just becoming the same thing with larger numbers. Monster is a good example, summoning more powerful creatures with different sets of abilities.
I actually like this idea, now that you mention it. I'm gonna tackle three of your questions first, and then present a new idea!
Speaking of Monster (and Animal and Animate, as well), the quantity and quality of the effect seem to be mildly borked. For 25 castings (1 + 3*8), it seems that you get 25 monsters (one per casting) from the SM9 list (SM1 + 8 SM levels for 24 extra castings). I'm not exactly sure what kind of scaling you were trying to accomplish, so I can't offer a proper fix.
It's trying to say that instead of getting 25 castings of SMI, you can have 1 casting of SMIX. Or that's how I interpreted it.
Light's damage is much greater than other remnants if I'm reading it correctly. But, it seems I'm not, as on re-reading, it appears that you need 3 castings to create a radius larger than 10 feet and thus deal damage. So I'm just going to go with it being mildly confusing and unintuitive, then. I think.
You put in 3 castings to get one ball of light, then another 3 castings to get another ball of light, etc... So, it's 4d6 damage for 18 RP, but with no save and no damage type, and only SR stops it.
Charm's RP cost is unusual. What happens if you think you have enough RP but actually don't when you try to cast it (for example, you think you're targeting your old drinking buddy, but you're actually targeting a Rakshasa disguised as him who has just noticed your party's Rogue preparing to slip a knife under his purse strings)?
Then it fails?
So... new idea. First... Monster, Light and Animal get changed as follows:
Animal
Conjuration (Summoning)
RP/class: DS 3
Range: Close
Duration: 1 round + 1 round/3 CL
Target: Summoned creature
You summon a single creature from the Summon Nature's Ally I list per casting of this remnant. At the end of the duration, any and all summoned creatures disappear.
Augment: For every 9 additional RP you use to pay for this spell remnant, you may use the next level list. (So, by using 9 more RP, you can cast from SNAII. By paying 18 more RP, you can cast SNAIII. Etc...)
Light
Evocation [Light]
RP/class: RM 6, DS 6, Mg 7
Range: Close
Duration: 1 round + 1 round/3 CL
Target: None (SR)
A ball of bright light appears that sheds bright light for 5 feet of this remnant in every direction, and dim light for another 10 feet beyond that.
Augment: For every 6 RP used to pay for this spell remnant, the radius of the bright light increases by 5 feet. If the bright light extends beyond 10 feet, a region of intense light appears around the ball of light with a radius equal to the number of feet beyond 10 that the bright light extends. Any creature within the region of intense light at the end of one of your turns takes 4d6 damage and is dazzled for 1 round. Undead take 8d6 damage instead. Overlapping regions of light caused by multiple separate castings of this remnant can stack to increase damage.
Monster
Conjuration (Summoning)
RP/class: RM 3, Sk 3, Mg 4
Range: Close
Duration: 1 round + 1 round/3 CL
Target: Summoned creature
You summon a single creature from the Summon Monster I list per casting of this remnant. At the end of the duration, any and all summoned creatures disappear.
Augment: For every 9 additional RP you pay for this effect, you may use the next level's list. (So, paying an addition 9 RP lets you use the SMII list. Paying an additional 18 RP lets you use the SMIII list, etc...)
As stands, this doesn't work properly for the magician, since he is supposed to be paying 12 extra, but I'm sure we can tack on a way to fix that if it's an actual problem. This, however, does allow for us to create some potent ways of bypassing our problems. For example:
Weaken
blah blah blah
Augment: A remnant caster of X level or higher may pay an additional Y RP to turn this remnant spell into enervate.
(Reword this, of course).
So, now, a RM has reason to get to Xth level. At higher levels, he can aim for higher effects, even.