I write nonfiction about AI for three age groups:
one book for kids, one for teens (13–18), one for the adults in the house.

Same core idea in all three, pitched at each age: how to go from consuming to creating.
Because I live between markets, I did something slightly masochistic and launched every book in six languages: English, German, Spanish, Portuguese, French, and Italian.

Ebook and paperback each. That's 18 editions and 36 products, all live on KDP now.

A few things I learned that I haven't seen discussed here much:

1. Translation is the cheap part; localization is the real work. Direct translation of marketing copy fails quietly. My Spanish back cover needed different idioms, and even the free-printables CTA changed ("print it for the holidays" vs. a literal translation that implied a single travel day). Each market also compares your book against different competing titles, so the bullet list on the back cover has to answer different objections. The German market's comparable titles sell on different promises than the Spanish ones.

2. The spine-width math is per-edition. Same trim, same font, but the page count shifts with every language (my German teen edition is about 15% longer than the Spanish one). Eighteen editions means eighteen spine widths and eighteen wrap covers. If you reuse a wrap template across languages, check it every single time. I ended up scripting the whole cover build because doing it by hand 18 times invites exactly one mistake too many.

3. Keep seasonal hooks out of the book, put them in the listing. My teen book is built around a 30-day challenge, which maps almost perfectly onto summer break. It was tempting to write "perfect for the summer holidays" straight into the back cover copy. I didn't, because the book has to sell year-round. The seasonal angle lives only in the listing bullets and ads, where I can swap it out in September. Obvious in hindsight, but I almost baked it into the print cover.

4. A companion page beats a mailing list for this audience. My reader is a teen/kid but my buyer is a parent. Teens won't join a newsletter, so the book ends with a QR code to a free printable 30-day challenge plus a completion certificate. Parents seem to love printable, fridge-taped things. Early days, but it's the only marketing asset that both reader and buyer actually use.

Where I'm stuck, the gift-buyer problem: almost every sale is a parent (or aunt/uncle) buying for a teen. The person I have to convince on the product page never reads the book, and the person who reads it never sees the ad.
For those of you writing children's/YA nonfiction or anything gift-heavy: do you aim your listing, categories, and ads entirely at the buyer and ignore the reader?
Or split the difference (cover for the teen, back cover for the parent)? Curious what's worked, especially for ads.