i am content and motivated after reading your write up.
i agree that there cannot be any generalization in design or design principles.
i am a space designer working on a signage project for India Habitat Centre, New Delhi, India.
i am equipped with design skills but need whole lot of info on “Signage design” and preferably the design process that follows.

does everything at the end of the day boil down to - “what suits the eye of the viewer”

Your article is a good start for a serious conversation.

As noted by other readers, the colour meanings you describe are somewhat arbitrary and very generic. I realise you were aiming to sum up more complex issues, but I believe that in the area of wayfinding and signage design generalised advice can lead to frustration and even accidents. When describing colour contrast and colour meaning, it is important to speak of ‘a blue’ and not just of ‘blue’, for example Navy blue or Marine blue, both of which elicit quite a different emotional response and achieve a different colour contrast with other colours.

Certain colours have explicit meanings and uses. These are prescribed by international and local standards and building codes. For example refer to ISO 7010:2003.

White background tends to reflect light and generate glare, which diminishes legibility, even when using matt surface finish. Unless you are using a combination of text size and thickness that compensates for this, it is advisable to avoid white background.

When discussing which colours to use, one must consider the physical context of the sign, as you suggest yourself. Not only do you need to have good contrast between text and background colour, but also sign background and the environment in which it is placed, or you start having people bumping into sign structures.

Another crucial aspect to consider in the context of ‘signage and colour contrast’ is colour-blindness. A colour combination that may seem to have sufficient contrast for people with full colour vision may not be suitable for all.

Please just let me know.

Thank you in advance.

Regards,
 Hendry