IANAS, but it appears that since these findings were obtained by a completely different process, they provide important confirmation of the Mars Express data--and extend that knowledge in an important way by adding location-specific information. From TFA:
"According to the team, the plumes were seen over areas that show evidence of ancient ground ice or flowing water. For example, plumes appeared over northern hemisphere regions such as east of Arabia Terra, the Nili Fossae region, and the south-east quadrant of Syrtis Major, an ancient volcano 1,200 kilometers (about 745 miles) across."