Hi
First about Lexeme:L5450 and Lexeme:L5451 I think they are different. See: https://en.wiktionary.org/wiki/zebra#Portuguese and https://en.wiktionary.org/wiki/zebro#Portuguese.
Second the derivation on zèbre I agree it's strange, and when I looked at this now first I'm kind of surprised that I modeled it. But I just looked again at https://pl.wiktionary.org/wiki/zebra#zebra_(j%C4%99zyk_polski) (with reference to archived copy of etymology dictionary http://web.archive.org/web/20160304221429/http://netsprint.swo.pwn.pl/haslo.php?id=29225) and https://pl.wiktionary.org/wiki/z%C3%A8bre#z%C3%A8bre_(j%C4%99zyk_francuski) and it really is there. It can be modeled differently when we base derivation on what's written on en.wiktionary but then we are back to the problem of importing from other Wiktionaries. I looked at https://www.etymonline.com/word/zebra and it is modelled with Italian. So we have four words to base: one Spanish (with reference), 2 Portugese (one with reference) and one Italian (with reference).
That's one of cases when we need some big pattern of etymology you mentioned here Wikidata:Property proposal/derived from form. If You have better proposition how to model etymology of zebre, feel free to change. I have it all in watched list and will observe. ~~~~