any relay could be stable its just a matter of performance and maintenance, you can ours for read/write for sure they are stable and based on strfry implementation.
Discussion
By that definition nostr.land is stable. Or nostr.wine. Even the 2 free ones (relay.damus.io and nos.lol) are stable. It’s odd because in the other clients I use (Damus, Nostur, Nostrudel and sometimes Primal), I only use the relays listed above and all my notes show up just fine. They were published to those relays. I wonder why that would be different on Yakihonne.
No other notes of mine have shown up on my profile when I added your relays, besides the 3 I told you about. A few days of notes are still missing.