“他演讲得很精彩”, is this sentence grammatically correct?
他演讲得很精彩 sounds unnatural because we mainly use 演讲 as a noun
for 'speech'. It is also possible to use it as a verb for 'to make a speech' in some context, e.g. 明天要上台演讲 (have to go on stage to make a speech tomorrow)

Use 演讲 as a noun and say &quot;他的演讲很精彩&quot; is the most natural way to phrase it.

If you must use 演讲 as a verb, it is more natural to say 他演讲讲得很精彩 or simply &quot;(這次演讲 - implied topic)他讲得很精彩&quot;

In most cases, the verb 演讲 can be reduced to just 讲


Example:
明天要上台演讲黑暗物質的理論 --&gt; 明天要上台讲黑暗物質的理論 (when you speak on a stage, it is giving a lecture/ speech)