unfortunately the site search for wikipedia is rubbish i always try to check before i create a new article that it hasn't been done before but googling the site first and also double checking in the categories seems to be the best way to do it the good news is you could easily merge your list into the pre existing ones and raise their quality by keeping the lists focused on one topic it would also be possible to illustrate every single insignia so long as there is a photo on wikipedia or commons somewhere like i said the list you produced was fundamentally of featurable quality possibly with a little bit of work but not much and there are plenty of lists on wikipedia that are of very low quality yet are inherently featurable if they got a little bit of tlc you seem to have the skills to do that so if you want to do some rescue missions there's definitely a job there for you with a rather nice reward at the end try not to be too dismayed