There are two main reasons for the fuzziness around definitions. Firstly, the lack of a common standard. The industry, at the hands of the CFO forum, did not manage to come to a single (European) definition and methodology on capital generation disclosures. In the Netherlands, the Dutch Association of Insurers (‘Verbond van Verzekeraars’) did publish a standard, but it only described the general, high-level principles, whilst still allowing for major discrepancies in the implementation and interpretation of that standard. Secondly, the objectives of measuring and disclosing capital generation figures vary among companies. Some insurers intend to either inform investors on the expected capital generation for the next reporting period, or show the company's performance in the past period, excluding (external) market influences. Other insurers use capital generation figures for internal balance sheet management only.
Using a different FCG definition than your peers is not necessarily a problem, as long as it is aligned with your company's objectives and applied consistently. Without consistency, the metric could allow for subjectivity, may lead to volatility and misinterpretation by its stakeholders, and cannot be fully adopted for monitoring & steering on the realization of your strategic ambitions.