Can I compute resistive device power consumption at specific voltage knowing its power rated at some other voltage?
Yes, that's correct. You can combine the equations

$$P = I\cdot V \text{ and } I = \frac{V}{R}$$

to produce

$$P = \frac{V^2}{R}$$

Which means that in general for a constant resistive load, power is proportional to V2.

So if the power at 220 V is 3500 W, then the power at 235 V would be

$$3500\text{ W} \cdot \left(\frac {235}{220}\right)^2 = 3994\text{ W}$$