Venezuelan Maldonado won this year's Spanish grand prix, but he also had a tumultuous season littered with mistakes.
The 27-year-old, who carries significant PDVSA sponsorship, has been retained for 2013.
"We win as a team and lose as a team," Briton Coughlan is quoted by Speed Week.
"Of course we've been through some difficult situations together and he will have learned from it. But it's not our style to point the finger at someone.
"It could just as well be argued that if we had given him a better car, he would not have been battling in the midfield so often."
Overall, Williams' 2012 season (76 points, 8th in the constructors' championship) was much better than 2011 (5 points, 9th).
"The biggest advantage has been the Renault engine -- light, powerful, reliable," said Coughlan, referring to the switch from Cosworth power.
"It meant we were able to focus entirely on aerodynamic development, and it paid off."