Hi there
Have JVM memory pressure above 75% is not a problem in itself, and often is cause by having too many shards (each shards [lucene index] allocate resources like memory).
Always you can add more nodes, but maybe the first question is why you need this amount of shards? maybe you need to request many queries and need parallelism?
Another principal origin of this heavy use of memory are expensive queries
You can check too how is the garbage collector behavior
Let me share with you a link to a elastic entry bog about to understand the memory pressure https://www.elastic.co/es/blog/found-understanding-memory-pressure-indicator/
and ... almost people know the limit of the JVM memory to elasticsearch is 32Gb (as you have) but on my personally experience I don config more than 30 because garbage collector is pretty playful (its my own think)
regards
Ale