What invokes a comma splice error? [closed]

Question

The results of the study were inconclusive, therefore more research needs to be done on the topic.

According to what I read, this is a comma splice. So it will be changed from ", therefore" to "; therefore,".

I am wondering if this is considered a comma splice error, because the transitional expression is a conjunctive adverb.
Does this mean that if the transitional expression is a conjunction like 'so', the sentence would be considered grammatical and would no longer have a comma splice error?

Like so:

The results of the study were inconclusive, so more research needs to be done on the topic.

Answer 1

Which means if the transitional expression is a conjunction like so the sentence would be considered grammatical and without a comma splice error?

Yes, for the exact reason you state.