Today the year lines are sorted by year, mint mark and the text in the line,
example from Luxemburg N#6420

As can be seen 2017 had the most common coin in the first position, because it had no text. In 2018 the most common coin ends up in the second position because of newly introduced marks “Lion / Mercury”. A year collector has to read each year line to make sure he gets the proper line, since the order has changed! Be that what it is, but see this 2017 coin, it has also marks (3 as far as I can see, and only 2 of them are documented! Nothing about the “signature”.

All this to say, that coins should be treated equally and coherently, the marks “lion” and “Mercury” are NOT shown in numista, neither where they can be found.
I suggest erasing the year line comments concerning the marks from 2018 up to now. The other possibility is to analyse all the marks of each year and add them to year lines (messy and of no use, since it's documented in the comments in text form.
I have the feeling this is a general problem with the euro coins from Luxemburh