yeah, this is fundamentally a client education problem, not a campaign one.
TOFU campaigns aren't built to show strong ROAS in the short term - that's literally the point. If your client is measuring top-of-funnel spend against direct revenue week over week, they're using the wrong metric for the goal they agreed to in the first place.
running a separate BOFU campaign to give them better numbers isn't wrong, but don't do it just to manage their mood. Do it because TOFU and BOFU serve completely different objectives and need to be measured differently anyway. Separating them is actually cleaner strategy.
what you really need to fix is the reporting. Stop showing ROAS on the TOFU campaign as the headline metric. show pipeline volume, cost per lead, audience growth, assisted conversions. ROAS should only be the headline on the BOFU campaign.
if they're still unhappy after that shift, then yes, it's either a funnel problem - landing pages, offer, sales process - or a product-market fit issue. no amount of ad optimisation can fix that.