Formulas in rows of matrix / Custom formulas in table rows

Okay, so here are some screenshots of a dummy project and the expected result.

First, the expected result in a quick and dirty Excel file:

A very basis P&L-like statement.

The key difficulties are the sales % and salaries % lines as well as the Marge on salaries and Special result lines. Of course, I want to recreate this table in Power BI, using a single matrix visualization with years as columns and those calculations as lines.

How to get there :

1 : The presentation table with the fields I want to include in the final P&L

2 : The Key table where I link accounts to type (field for the P&L) and to transactions

3 : My formula table where I want to create my custom formulas to populate my P&L. I want to be able to calculate those values as lines in the P&L. This table may lack the sales% and salaries%, but if a solution is found, I would just need to duplicate it for all the formulas I wish to use.

4 : The transactions table I use to calculate all the aggregates for the P&L

Hope it's a bit clearer. Dummy project for reference :

https://nofile.io/f/PYwOEhO9MVx/Dummy.pbix