This may be of interest to some.
I have been painting models for 55 years, using mostly Humbrol, which I find has excellent qualities.
My collection of colours includes pre-mixed Humbrol tins in the historical railway colours (from the 1970s)
The paint's gloss finish is perfect for decaling.
I have tried other brands as well.
With the weather here, I can both brush and spray outdoors.
For spraying dilution I usually use the proprietry solvents sold at hobby shops.
For brushing and cleaning, I use any solvent available.
In Australia, that tends to ube mineral turpentine, as it is available in bulk.
However, all these solvents do cause some discomfort to my breathing apparatus, if I am using them for an extended period.
In the last few years, I tried "low-odour" turpentine, with little improvement.
Recently I tried plain old eucalyptus extract (oil), which is available anywhere here, both chemists and High Street markets.
I found it perfect, because I also use it as a nasal decongestant anyway.
Spraypainting is now done rarely, so I doubt if I will get around to trying it as a spray solvent/dilutant, but I cannot see why it would not work.