Pronouncing Pneuma

I would not say that it's wrong to pronounce πνεῦμα without the 'p,' (i.e., "neuma"); it's more a matter of linguistic convention and illustrates how phonemes come to be pronounced in another language. A variety of English dictionaries include pneuma--you can see their pronunciation schemes here:

https://www.onelook.com/?w=pneuma&ls=a

For example, Merriam-Webster has ˈnü-mə for pneuma. Other works give comparable ways of pronouncing the word.

However, when it comes to the Greek, William Mounce writes:

Remember, in Greek there are no silent consonants, so the pi is pronounced; unlike in English where, for example, the "p" is not pronounced in the word, "pneumatic."

See https://www.billmounce.com/greekvocabulary/%CF%80%CE%BD%CE%B5%E1%BF%A6%CE%BC%CE%B1

Either way, I'm not going to castigate or flog anyone who pronounces pneuma without the labial voiceless plosive.