Bogenhafen is still about though I think it was largely included by the 6th edition due to how well regarded Shadows over Bogenhafen had been as a WHFRP supplement. The Empire has numerous towns but few, save the main city states, have ever really had their liveries represented. WHFRP gives a few more of the Reiklands large towns but the FB end never did much. Uniforms and Heraldry is honestly a rather sad book for interesting color or regional flavor, most of the heraldic devises are just copy and pasted with different color schemes across a great number of the provinces.
On the Ostermark note, it skews maroon over purple since the cost and availability of purple dies are not the greatest in the eastern Empire.
That probably explains it then, if it got a lot of focus in WHFRP I guess it was 'in vogue' around that era, then over time it's just faded away out of the spotlight. I suppose when these places are chosen as specific settings they get some fluff to make them significant and pad out the locale, it just then ends up making them seem far more important maybe than other, equally sized, named towns around the Empire that just never got attention in the same way?
I agree regarding the Uniforms and Heraldry book, I was fairly disappointed seeing the same blokes colour blocked differently across the pages if I'm honest. It could have done a lot more but hey ho, it serves a purpose as a bit of a reference. I take more inspiration from the combinations of patterns and stuff that I maybe wouldn't immediately think of, my brain is very much block colours so any influx of stripes and checks or colours in unusual places just gets the juices flowing.
Also Ostermark - my default is usually to envisage a deep maroon with a faded almost pastille yellow, somewhere in between the two as a happy medium
