"if only barely" is correct and usable in written English.
You can use it when you want to express that you are doing something, but it is only barely enough to be successful or sufficient. For example, "I was able to pass the exam, if only barely."
More removed experts call that wishful thinking, if only barely.
Once conference play began, however, Caltech found itself in its usual place — on the wrong end of the score, if only barely.
The new calculation of the flow of oil, if it holds up, suggests that BP's latest plans for capturing oil will be adequate, if only barely.
Democrats parry by pointing toward constituent service, hoping that their financial edge and the conservatives' overreach will leave them in control, if only barely, of Capitol Hill.
Rather than trying to live up to some eternal standard of formalist excellence, Mr. de Keyser is looking for something that feels alive, even if only barely so.
And like any heir of Patsy Cline — a receding but still relevant influence — she kept the lid on the boiling pot, if only barely.
(If only just barely: one of the men The Paris Review editors discussed meeting with about editorial matters in the early 1960s, he notes, was the sociologist Daniel Bell, who "essentially invented the neoconservative political movement that would inspire George W. Bush in his disastrous invasion of Iraq").
With pre-orders opening up today in the US, the company is unveiling the price of the phone, which comes in, as promised, at under $300 – if only just barely.
Regret, sorrow and incomprehension can be detected, along with sweetness and stubbornness and an unwillingness to give into cynicism and despair — if only just barely.
It makes the awe-inspiring and perhaps intimidating quality of classic Hollywood movies seem more real and attainable - if only just barely.
And if he loses or if he only barely beats Forbes, it will be seen as a further sign of weakness".
