It is strong evidence, because knowledge acquired developing the company's own product is by definition knowledge of that product. The petition still has to describe what the knowledge consists of and distinguish it from general engineering skill.
The development history answers both parts of the test
Hypothetical example: the engineer spent three years designing the chute, running the test programme and resolving field failures. That history supports two elements at once: what she knows, and that she acquired it through employment with this company. Set it out as items rather than as a narrative — the hydraulic sequencing logic, the tolerance decisions, the fixture design, the modifications developed for particular installations — and attach the drawings and test records behind each.
Then state plainly what is not specialized: her mechanical engineering education, her general knowledge of hydraulics, her familiarity with common fabrication practice. The remaining requirements still apply: a qualifying corporate relationship with both entities doing business, one continuous qualifying year abroad within the last three years, an assignment that is not the supply of labour to a third party, and a five-year ceiling on time in the status.