Thank you for your recommendations!

Hopefully I'll get around to take Zed for a test drive in the near future.

As for GNOME Builder, for some reason, I wasn't able to replicate what's seen above with it. Perhaps it doesn't support Markdown that well. Or..., it needs/requires a plugin to do its bidding. Would you happen to know more on this? Any help is appreciated!

KDevelop and Kate, on the other hand, have been a very pleasant surprise. I have literally checked about a dozen of text editors since yesterday, and these two have been the only ones that have yielded the desired result. Props and kudos to the dev team!