When I tried to bold-face words spanning comma for English grammar questions that whether or not comma should be used, e.g. "unified**, will** induce the risks of strangling the usage of ...", that comma and following words put inside pair of double asterisks won't bold-faced in preview. I may not understand the correct way to do that or it's just how things are designed this way? I ended up moving the opening double asterisks in front of the word before the comma I wanted to highlight.
This is by design. Absent a spec for SE flavor of Markdown, I refer to CommonMark spec:
A left-flanking delimiter run is a delimiter run that is (a) not followed by Unicode whitespace, and (b) not followed by a punctuation character, or preceded by Unicode whitespace or a punctuation character.
A double ** can open strong emphasis iff it is part of a left-flanking delimiter run.
So, one cannot bold a part of text beginning with a comma using Markdown. One can use HTML though:
unified, will induce
unified<b>, will</b> induce