Have you tried Catawiki auction site? Many models of that ear were also by Carrette, so if you can locate any info. on those, you can at least compare them. The next post I see on I.G. of the person who has many like you, I will message you the account name. You might try searching there for antique Marklin #hashtag as well.

While it's true there is not a lot of reference available in English, you might find some of the books from the series "Technical Toys in the Course of Time" to be worth a look.

15 volumes in total, with the first 5 covering the period up to WW1. The series is in three languages, German, English, French.

I have two only from the series, #4 & #9, but they are excellent reading in their own right, and may have some of the information you are looking for.

I'd gladly have more (the full set) but postage from Europe is the killer.

Vol 4 contains reprints of several catalogues, the index page is also attached.

Note that while the preface and item descriptions are multi-lingual, the catalogue reprints are German-only but the original catalogues were printed in English also for the US & UK markets.

Further, these are full catalogues so they contain the entire Märklin range, not just trains. Impressive all the same.

HTH

Cookee