Interaction implementation issue for mock-up designed using Adobe After Effects

I'm a front-end developer. Closely working with HTML/CSS/JS/Angular/Bootstrap

I'm getting signed-offed mock-ups from Adobe After Effects(AE), which is done using same Adobe Photoshop(AP) files exported to AE. These are provided by external design agency, they do UX and UI. Sitting with client they gather requirements and validate with users.

Customer has given sign-off to design and motions based on AE and AP files done by design agency.

Even though I have implicated pixel perfect static file as same as AP files, I'm unable to meet motion level as same as AE given by the design agency. Like its not smooth, quality of ripple effects ect..

As the development team, we are struggling to convince client limitations while implements them to functional prototype. I got few questions to ask,

• What is the mistake we are doing as a development team?
• Do we have set of principles to produce design agency follow, based on technical limitations?