First of all, if you do really borrow capital (which is a viable way of financing you working capital), the costs of it, that is interest paid, are already included in W_t1 (yet another entry in total costs). Furthermore, inflation means that the price which you sell your goods at also rises, so your extra cost of inflation will be offset in the revenue. And last but not least, you can indeed write something like R_t2 - W_t1*(1+(t2-t1)*i), but this will be not what you likely wanted to say. What is i here?
The nominal interest. Because the capital you blocked at time t1 for buying your goods at that moment, costs you an interest i.
The nominal interest is the real interest plus the inflation rate.
p is the inflation rate, i is the nominal interest rate, which equals i0 + p.
To R, you should only apply p of course. To W, you apply i0 as well as p. But essentially you do the same as I do, yes: the increase in output at time t2 because R rose nominally because of inflation is compensated by the higher interest you have to pay on your loan of W because of inflation when R = W.
In other words, whether there is inflation or not, if R = W, the "higher nominal sales price" will be compensated for the higher interest rate you have to pay on your loan of W because of inflation.