'problematic past' is correct and usable in written English.
It is typically used to refer to a period of time that was especially difficult or troublesome. For example, "The country's history has been marked by a problematic past of oppression and war."
In Britain, meanwhile, another comedy star is grappling with a problematic past.
You need to be able to deeply understand the profoundly problematic past of this great nation.
All credit to the Walt Disney Studio, then – an outfit that has had a fairly problematic past to overcome.
In a contorted way, many Israelis believe that the new wave of Palestinian terrorism has granted their country absolution for its problematic past.
Mr. Fong, with a problematic past and an ailing mother, stayed behind and later became head of a provincial power company.
As I grew older I said "Iranian" — never mind the label's problematic past, I was concerned with owning its problematic present.
The key thing in that case – and indeed in the vast majority of cases where organizations distance themselves from their problematic pasts – is that the law was bearing down on them.
Criminologists and police officials said smaller departments and those that lack sufficient funding or are understaffed are most likely to hire applicants with problematic pasts if they have completed state-mandated training, which allows departments to avoid the cost of sending them to the police academy.
It came to national prominence over the last few years as both Canada and the United States have grappled with how to commemorate their problematic pasts.
The 250 MHz system was employed in order to mitigate the potentially negative effects of the lossy substrate, which had proved problematic for past research using higher frequency antennas.
It's an utterly broad and unsexy set of criteria one that will prove less problematic than past cheeky and explicitly pornographic campaigns.
