I am interested in some of their products too. A while ago I did a search on their parangs and stuff and came up with a few reviews, which generally were very positive. You might even find something on this forum. Don´t know about the company´s service though.
"Spring steel" is usually 5160 or comparable low chromium alloyed (non-stainless of course) steel. Excellent for long or highly stressed blades. If the heat treat is right, one of the best steels for long blades you can get.
Reason why they call it "spring steel" is they probably recycle vehicle leaf springs, which usually is a cheap, but perfectly acceptable way of getting steel in the Phillipines, Malaysia, Indonesia. The automotive industry standard for leaf spring alloys is 5160, and an experienced smith probably notices if it´s something different in forging or heat treating/testing.