"There are! Proceeding with that in mind, I can think of three techniques which you might find satisfying, all fairly well-reputed and orthodox.
The Four-Yin Spymaster Art is an Academic technique with a Hidden secondary element, relating to - well, idealising the spymaster's role. It emphasizes perception, contextualization, and information synthesis rather than volume of information intake or planning ability, though it is holistically effective - I wouldn't recommend an art which isn't. Its mental refinement is purely passive, but its perception enhancement includes numerous active elements. I think this should alleviate your worry about mental integrity - you might feel as though you have been rendered blind to the world, but you would retain your own internality. The technique is cultivated entirely internally - albeit, it depends on secondary techniques to conceal its qi signature, and it has a very good pedigree - it was obtained from a now-deceased rogue cultivator who used it to reach the 6th realm, and Bank students employing it have reached 4th on several occasions - we normally don't recommend it to those seeking to become spies, there are better Hidden-primary arts for the stealth and covert communication aspects, so that's out of 37 people having taken it. The technique sees use outside the Bank as well, including another recorded 4th realm, but proper statistics have yet to be compiled.
The Perfect Curious Spirit is a foundation derived from the innate practices of heart-devils with Academic primary aspects. It unfortunately does depend extensively on active qi usage - it's one of those arts which blurs the line substantially, your intellect will wax and wane noticeably as your qi expenditure on it does. However, I would say in all other regards, it's our strongest academic art designed to provide holistic non-specialised intellectual enhancement or enhancement for general-purpose learning, selected from those arts which do have substantial other requirements and which permit purely internal cultivation. It has a misleadingly good pedigree - a 6th realm and two 5th realms, but they were all heart-devils already well-suited for this sort of cultivation, a mortal will have a harder time wrapping their head around it. Ironically, an art devoted to learning is itself difficult to learn. We have still seen good results, though.
The last art is the Great Academy Immortal Education, developed by our fellow sect, the Great Academy and sold to us as part of a program to improving the prevalence of high-level administrators in the empire. Purely passive mental refinement and cultivation based on memorisation and calculation is combined with the creation of an internal calculation engine, which can do simple cognition with incredible efficiency, including rapid casting of extremely cheap simple techniques and administration tasks which no mortal could reasonably comprehend. Again a form of enhancement whose lack is crippling but not compromising. It's a more sophisticated version of the standard techniques taught to imperial bureaucrats, and thus has had more storied users than I can summarise easily - suffice to say, two 6th realms and a 7th, albeit all at the Academy. It also has an immense library of techniques, both inside and outside our library, designed for explicit compatibility with this line of cultivation techniques, though I will warn that the majority of them were designed to be easy to teach to mediocre cultivators and are thus not very good."