Is the engine oil and the transmission oil fed from the same tank not refering to the clutch-primary oil?

No, the engine oil and trans oil are not fed from the same tank on H.D. bikes. Engine oil is separate, from the primary drive chain on 4 speed big twins, the transmission oil is also separate. Sportster engines have separate engine oil and their transmissions share primary case oil with the wet clutch. 5 speed models wet clutch models have separate primary case lube, transmission lube and engine oil. As far as my memory serves, no Harley Davidsons have shared engine oil and transmission oil similar to some Jap bikes