even is nowhere near an engineer, but they are, by necessity, a quick learner, and by nature, someone who will acquire whatever skills they think are necessary to make themself invaluable. combine that with the fact that the Doctor’s TARDIS is in a constant state of on the fritz/in need of repairs/just being tinkered with by him because he’s bored, and they do pick up a few things. (and obviously, to someone whose entire life has been dependent on their ship Functioning Or Else They’re Fucked In Deep Space, the TARDIS being damaged even slightly is stressful! they want to know how to fix it! they won’t die immediately anymore (probably) if the ship they live on malfunctions, but it’s hard to shake that instinct.)
Which means even does have a pretty thorough knowledge of how to repair and recognize TARDIS parts. Without really knowing what they’re doing, but knowing how to figure out a solution, even if they have to brute force the answer. Think of it like trying to do physics without having any understanding of calculus and instead having to use algebra — completely possible, but frustrating and much more likely to lead to mistakes — AND also the guy teaching you is a substitute teacher who speaks in a language he made up for his D&D group half the time and if you ask him what a word means because you can’t understand what the fuck he’s saying, he goes off on tangents about the etymology of it, forgetting that he’s supposed to be teaching you. physics. they have the world’s most convoluted understanding of how a TARDIS works, but like. about 75% of the time they can identify what’s gone wrong and 50% of the time, they might even be able to solve it themself if they can find the right tools. (*success rate will vary depending on level of stress they’re under.)
(to a much lesser extent, the same goes for piloting, although that’s much more cause-and-effect observation combined with information the doctor throws at them in the heat of the moment. which leads to a knowledge base that’s a bit like not knowing how a car’s steering wheel works, but definitely knowing where both the blinkers and the accelerator are and how to make use of them. even very much cannot fly a tardis alone (or, not effectively. MAYBE through space if they’re under pressure, but they don’t have the sense for time that time lords do. not hooked into that matrix.) but they know enough to be very useful to someone else flying one who can direct them.)