The emphasis in my work is primarily to enable people to cleanse their subconscious suppressed energies. This is nuts and bolts psychology. When we get into talking about the Higher Self, we are getting into a speculative area where very few people can be regarded as experts, and I would not be one of them. It is thought that there is a Higher Self, and also that it is normal to not yet be in touch with it. Getting in touch can be regarded as one of the goals. But certainly, if you feel remorseful for not yet being in touch, you are beating yourself up for no good reason. I would not advise anyone to be fixated on this, there are probably more serious issues in the lower chakras to work out, and maybe you are avoiding them by the fixation. It might be enough to just assume that you are being guided by your Higher Self, even if you are not consciously aware of it.
If you experience 'airiness' or disconnection from 3D reality, processing the airiness would probably help, as well as emphasizing grounding. But will processing help increase the Higher Self connection - possibly, but of course there are other practices that will help as well but that's not really my area of expertise. It is part of my regular meditation to feel that I have shifted to my Higher Self by focusing on the crown chakra and seeing myself with raised vibration and sense of expansion, surrounded by a large ovoid form, but that's my personal thing. Let me again remind you that Witnessing is a main route to activate the Higher Self. As the Witness identity builds, it overcomes lower-self identification and constructs what leads to Higher Self realization. You can practice witnessing with lower chakra issues.
These are subtle questions that pertain to your personal psychic make-up. I think you are probably right that the depersonalization (I've never heard that term before) is an involuntary avoidance mechanism, to stay conscious of and to try to minimize as much as possible with grounding and witnessing. But there is actually a lot of talk on the internet (e.g. David Icke, Matrix) about the 3D world being a simulation, so it could be that you are seeing things as they really are, raising your consciousness, instead of buying into the simulation. In this case, careful cultivation of this sense would be called for. You could be opening the psychic door, and you want to be protected, with the light. On the other hand, airiness, lack of grounding, inability to lock into the 3D world and contend with it as needed, which is part of our mission here, can be a problem. You do need to be able to function on the earth plane. I would work extended with the induction - the protective light, the grounding earth, the witness, and occasionally go up to the crown chakra and feel yourself to have shifted into the Higher Self. And sure, stay with all the info in the books and work on all levels. Good luck.