@Mackcrabs, you've had a little on 'cons' now for a 'pro' .
I would
not avoid walking into Santiago at Easter, rather the opposite in fact. I walked into Santiago on Easter Friday 2023 (along with well over 3,000 others spread across the various caminos), the experience was
incredible. The atmosphere, the parades - I absolutely loved it. An experience I felt privileged to share.
Walking into any major city during Semana Santa would likely offer a similar experience.
There is in fact a thread from the rev asking about which town or city he
should visit during that period, hopefully somebody will find and link it.
As a general rule I do not like crowds. I am not religious & I knew nothing about Semana Santa. That week was the only week that I had to walk. So I started the Camino Inglès expecting the eight to ten pilgrims that people of the forum were reporting the week prior - and found I was walking with around 100!
Fortunately, because of my time constraints I had pre-booked all of my accommodation. So with this potential worry out of way I was free to simply enjoy. (Others struggled to find a bed at times, at Bruma many had to taxi or walk a further 10 kilometres.)
The Frances will have similar pinch points; you don't mention your start Point. If it is SJPDP then the usual advice would apply - start slow, (even potentially break up the first day) & book through to Pamplona. Or even a day or two beyond to get you past Easter. As mentioned above, even just a few days after Easter things will quieten down considerably. The section hikers predominantly drop off at the weekend, normally at a major town or city ( transport).
Consider timing your entry into one of the major towns to try and enjoy the beauty of this almost unique experience. I'm not sure if that should be Pamplona or not, I guess it depends on how well you do with crowds.
Despite the 'crowd' on trail I found plenty of opportunity for time by myself, at others I enjoyed the company.
Contributors have often commented that even during the busiest of periods on the Frances they can find solitude when desired. (And a bed!).
Weather is very unpredictable and the best we can do is look at historical records. Which shows that pretty much anything can happen. Sometimes April is actually nicer than May. Either way it's spring, a beautiful time of the year.