If TAF proceeds, a new class of outside investor will be able to own dividend rights to Fonterra shares.
The co-operative's 10,500 farmer-shareholders are being sent a voting pack on TAF this week, before a vote on June 25.
The restructuring bill will enshrine Fonterra's price-setting manual in law and the regulator wants to be sure the world's largest dairy exporter is encouraged to operate more efficiently and not freeze potential rivals out of the industry.
The commission said its initial review was a limited version of what it would do in reality.
Although most of Fonterra's assumptions were reasonable and practically feasible, it did identify "a number of Fonterra's assumptions or approaches that do not appear to be both practically feasible for Fonterra and reasonable [ie, able to be achieved by another efficient processor]", the report said.
Among the most significant were Fonterra's use of depreciation rates to calculate tax expense that are below the rates specified by the Inland Revenue Department, which the commission said could have the effect of decreasing the base milk price.
Fonterra also uses debt premiums in the United States in determining the cost of debt "but makes insufficient or no allowance for the additional costs incurred by NZ-domiciled operations" such as cross-currency swap costs and debt issuance costs.
The commission also identified another category of assumptions, such as sales and labour costs, where it did not have enough information to conclude if they were reasonable and feasible, the report said.
It makes recommendations for tweaks to the milk-price manual, including more complete disclosure of key quantitative information used to calculate the base milk price.
In a table it lists 12 issues related to Fonterra's revenue and costs, of which it concludes half are deemed not transparent to third parties, while under the heading "Gaps in Fonterra Information and Analysis", seven of the 12 note limited data or analysis, or lack of reconciliation between modelled and actual figures.
The commission did the review at the request of Primary Industries Minister David Carter and is seeking submissions by June 29.