I never gave RMC that much attention. Since I have every earlier version of the game books, I didn't really see a need to buy them get again.
It's now obvious that the editors of that product either didn't fully understand the works they were editing or at least failed in the goal of taking out the obsolete or confusing parts to make them more accessible to a modern audience (or whatever equivalent marketing jargon they used to justify it).
RMC Spell Law should have a disclaimer somewhere in the Introduction section about using Spell Law with the complete Rolemaster rules vs. using it in combination with other Systems. Here's the relevant text from the 1989 version of Spell Law.
The rules in ChL&CaL are intended to coordinate and combine all of the individual RM systems. Thus the rules in ChL&CaL should take precedence over the rules in the other individual products when the complete RM system is used.
If you can't find something like that then the RMC editing process was definitely a failure.
OK, so now for the history lesson on how we got here:
The original Spell Law rules had the idea of "Spell Expertise" in the Elemental Attack Spells section. By the 1989 edition that was replaced with a boxed section called "Directed Spell Skill" that reads:
By spending time and effort in practice and use, a caster may develop Directed Spell skill in using certain elemental spells. This is dependent upon the character development system used.
At each level of experience, a spell caster may increase his Directed Spell skill with one elemental attack spell (that he can already cast) by one "skill rank" (his choice). This means his Directed Spell skill with any elemental attack spell is not a direct function of his level. The spell caster's Directed Spell skill rank with each of these spells must be recorded.
A spell user's Directed Spell skill bonus with a specific spell is a +5 for each of the first 10 skill ranks, a +2 for each of skill ranks 11-20, +1 for every skill rank over 20.
GMs employing this rule may want to allow extra development of Directed Spell skill through practice and/or research.
In that 1989 edition those boxed sections were intended for use by people mixing Spell Law with character development rules from some other game system and were to be ignored by those using the rest of RM.
By the time we get to the RMSS version of Spell Law, all of the main rules have been moved into the "Rolemaster Standard Rules" book. What's left in Spell Law is an Appendix B titled "How to Use Spell Law without Rolemaster" and it consists of a cleaned up, slightly modified version of the old rules. It starts with the disclaimer:
This section presents a set of guidelines for using Spell Law if you do not have access to the full Rolemaster system. Certain rules have been simplified or changed to make it easier to use for those unfamiliar with Rolemaster."
Then in the Elemental Attack Spells section we find a Directed Spell Skill section that's identical to the one from the 1989 Spell Law.
So it's safe to say that RMC took the liberty of further simplifying that text about Directed Spells and the key point being missed here is that the rules listed in Spell Law are meant to be simplified placeholders overridden by the rules from Character Law, Campaign Law, and even in some cases Arms Law. Spell Law and Arms Law came first. Character and Campaign Law completes and (sometimes corrects) the rule set.