I assume you're asking about Attempt and Contest rolls? If so, no, you use the actual Level.
Most of the time you'll be making Skill rolls, not raw Attribute rolls, but in either case, Attempt and Contest rolls are both 2d12 + Level + modifiers. This is what it says on pg 17, under the section 'Attempt Rolls' (or rather, it doesn't say anything special about Levels over 12).
You also use the actual Level for all Asset calculations. Again, see the formulas on pg 185; nothing special there about Abilities over 12.
If the calculations are confusing you, feel free to check out this autocalc Google Notes sheet I put together: https://docs.google.com/spreadsheets/d/1emMUr5PFAq0sYScTIkTdbet_k75n3YAN021RafEI...
Again, hope this helps, thanks!