If it was a new service, this should have ruled you out (for Harvest's case) before you became a qualified lead. I was trying to ask about something that you could use with a workaround (like a few more steps create a translation) or offer to write what was needed to translate for an additional commitment from you. Would you have taken one of those options, or was the client facing information needing to auto-translate a deal breaker for you?
I actually used Harvest for a while, and I basically changed all invoice labels to make them bilingual.
I ended up switching to Pancake, it actually supports setting a per-client locale, and the client-facing parts are translated correctly. It's still not perfect, though, but at least it's there.