The tool would help create impact statements, stories and reports

One of the fundamental baselines for the social venture sector is an understanding of where a profit-for-purpose model lies.
The tools and the models are readily available for social ventures; Business Model Canvas, Value Proposition Canvas, Lean, Sprint, MVP, Lean For Social Impact, Logic Modelling and Theory of Change are all relevant.
BUT in a world drunk on lightening iterations of Build, Test, Launch, Repeat > Fail And Quit/Pivot/Scale we have a fundamental end game problem:  Profit (and I do not mean sustainability) and Exit Strategy.
Social Ventures may seek sustainability (and even profits) But almost none have an Exit Strategy.  JustGiving does not, nor does Tom's Shoes.  And that is where the investment, and indeed the interest, in Digital Social Innovation/Ventures fails to materialise.
Social Innovation seeks to create savings or efficiency on future societal costs.
BUT Many developers and engineers see projects as products with exit strategies. Working at costs for equity and hope to hit the jackpot project.  And so do investors. many of who do not know, understand, or care much for digital social innovation or social entrepreneurship. There is usually no new IP or patents to be sold on either. 
The answer to  "How can we better develop and support entrepreneurs in Wales and help them maximise social, environmental & economic impact?" may actually be a firm collaborative approach with the Private sector FOR support and investment via CSR.
This may circumvent the current funding rules of social enterprises and the 51% profits return rule.
But before that there needs to be a robust education campaign on what social ventures are. the misconception of Exit Strategies in the sector and what sponsorship of them can give Private Sector Investors or Patrons.