I think what you have is a williamsianum hybrid and not the species. The species itself is very distinct in appearance with relatively small, almost rounded leaves and large pale pink flowers held in loose clusters of 2-3 rather than large, mounded trusses. Your plant looks nothing like any williamsianum I've encountered!

Rhododendrons really don't need any pruning......in fact, they don't require much care at all other than to ensure proper soil pH and watering as necessary through the summer months.

You can prune back if you feel you need to and now right after the bloom cycle is a good time. Be sure to take any cuts back along a stem to where another branch emerges or all the way back to the main stem/trunk of the shrub. Don't leave any stubs. What may look like dead stems are most likely not :-) From what I can see, all the bare gray stems - just old wood - end in new growth.

If you have more concerns, please post more photos. I don't see anything in the one you posted that would make me rush out and want to prune :-) The plant looks to be in very nice condition.

I do not prune rhodies either but I leave space when planting so they can attain the estimated size at maturity in the plant's label. With only one picture, I could not see what was the reason for pruning??? Can your partner confirm yes/no if this pruning is necessary?

Rhododendron Williamsianum hybrids bloom around April/May-ish so, if you have some need for pruning, soon after blooming is complete would be the right time to prune.

Dead wood can be pruned at any time. If not sure that you have dead wood, you can do a scratch test against the bark very carefully to see if you see "green".

I’ve taken a couple of photos, maybe if I feed it well now it will help with flowering,

It blooms only once a year (Spring). At some point "soon-ish", it will develop flower buds for Spring 2021. They will open at about the same time that you saw flowers this year.

If there is in fact any williamsianum at all in the genetic background of the plant shown here it is not apparent in its foliage.