Scotland scored the first and last tries of the match - through Damien Hoyland and Jamie Farndale - but, as was so often the case during this year's tournament, defence let them down.
And with a Junior World Championship this summer in New Zealand to prepare for, Lineen admits that improvements are needed, and fast.
"We've got a window now to get prepared for New Zealand and it doesn't get any easier," he said.
"These guys are learning all the time. I'll be seeing them through this period to give them everything we can to prepare them as well as we can.
"But we're up against outfits that are a bit further down the track."