A welcome flow needs a human check before it sends
An automated welcome sequence saves you real time, but it should never run completely unsupervised the first time it touches a real client. Names get mixed up. Merge fields break. A message meant for one type of client goes out to the wrong one entirely.
The fix isn't to avoid automation — it's to add a short human check before each message actually sends, at least until you trust the flow completely. I still do this myself with every new sequence, no matter how simple it looks. That can be as simple as a daily glance at what's queued, or a rule that holds messages for review before delivery goes out.
Once you've watched the flow work correctly for a good stretch of time, you can loosen the check. But skipping that early review is exactly how a client ends up reading someone else's name in their own welcome email.
Try this today: look at your welcome sequence and add one review step before each message sends, even if it just means reading it once before it goes live for real.