Echoes is always the hardest part for me, and I'm a bit peeved at how rarely OW actually stats out what they think it does for various NPCs. They just add the power and an animal name at most, but no info on what the bonuses are for that creature. One single NPC (Korrick) gets a note specifying a +1 to Athletics when the animal nature could benefit him. This is out of 8 different beings in What Goes Bump (counting all were-beings as one, and both types of BCV as one) and 6 individual NPC stat blocks.
Aaaanyway, excuse the rant...
For a Lynx, I think what you have is completely valid. I could also see something like:
Beast Trappings: Lynx are stalking predators; +1 to Stealth when Shadowing
Beast Senses: Lynx are nocturnal; Ignore up to 2 shifts of increased difficulty due to darkness.
Beast Friend: Feline