In my research, one finding that stuck out [2] was that natural oils (triglycerides, saturated or unsaturated) are more pro-inflammatory than straight-chain mineral oils. MCT oil would absolutely cause acute inflammation and in severe cases, collapse of alveoli.
However, the long chains, longer than C14, have half-lives measured in months to years. The effects of these is harder to know, but excessive exposure causes essentially COPD.
Edit: oh look, here's an article specifically pointing out lipoid pneumonia [2]. I actually disagree with their thesis, that vegetable glycerine is causing the inflammation. I would bet it's more likely to be one of these thickeners, or a carrier agent for a flavor, causing the inflammation. I know people who go through over an ounce per day of VG solution that aren't getting chemical pneumonitis, but inhalation of sub-milliliter amounts of oils has sent friends of mine to the hospital.
Basically, if it's not air, it doesn't belong in your lungs. However, the degree and character of the damage done depends on the chemical composition.
Shorter molecules, molecules with more hydrophilic nature (alcohols, polyols, ketones, acids), biologically active molecules, are more acutely inflammatory, but usually the body can deal with them. Longer molecules, biologically inert ones, are less acutely reactive to the immune system, but can cause disruption of membranes and long term toxicity. Unsaturated fatty acids are especially bad because they can be oxidized directly into inflammatory signal chemicals. [4]
[1] https://en.wikipedia.org/wiki/Chemical_pneumonitis
[2] pdf - https://www.ajronline.org/doi/pdf/10.2214/AJR.09.3040
"Mineral oil (a mixture of inert, long-chain, saturated hydrocarbons obtained from petroleum) and vegetable-based oils tend to cause minimal to mild inflammatory reactions (Fig. 3). The intraalveolar oils can coalesce in the alveoli and become encapsulated by fibrous tissue, resulting in a nodule or mass (paraffinoma) (Fig. 4). Conversely, animal fats are hydrolyzed by lung lipases into free fatty acids that trigger a severe inflammatory reaction that manifests as focal edema and intraalveolar hemorrhage [5]. "
[3] html - https://casereports.bmj.com/content/2018/bcr-2018-224350
[4] https://www.frontiersin.org/articles/10.3389/fimmu.2014.0048...
"unsaturated fatty acids can be oxidized in a tightly regulated and specific manner to generate either potent pro-inflammatory or pro-resolving lipid mediators. "