Zoro never lost any 1 vs 1 after his promise. A clear fight to become stronger.
Vs eneru, it was like rooftop many vs 1 or 2 because of their overwhelming power. Zoro got beaten but eneru being a logia with only one weakness (rubber) wasn't for zoro and a group fight like Kaido and Big Mom (being yonkou).
I mean Mr.1 was only for Zoro and Oda made him win so if it was a 1 vs 1 death battle, well it's different...
Lucci wasn't a fight but a clash who btw just threw away luffy and zoro. We all saw what happened to lucci and cp9 after that lol.
The only real defeat was against kuma when zoro didn't know what to do and gave up. But Kuma gave him a challenge that Zoro succeeded so Zoro didn't lost to Kuma neither.
Why you think Oda brings always the line "I can't lose " for Zoro when from many point of views Zoro already lost multiples times ? Is Oda dumb that can't count or his éditors and full shueisha also ? Lol!
In Oda's eyes, Zoro never lost.