This is the first picture from that post. It looks sort of Carissa macrocarpa-esque: there are several strange cultivars with which I'm not familiar. Does it have any thorns? Milky sap if a leaf is broken?

Maidenhair ferns sold as houseplants tend to be almost exclusively selections of Adiantum raddianum. And one of the trickier houseplants to grow well indoors. Lack of humidify and any mistimed watering can do them in pretty rapidly. This is a tropical maidenhair (Central America, West Indies) so not very cold hardy. If you live in zone 9b and above, you can expect it to survive outdoors, even more likely if grown in a container and moved into protection if colder than normal weather is anticipated. How much 'hardening off' is required will depend on your location and current temps. And it's a fern for heaven's sake, so of course no direct sun!!

separate it.. and dont worry about hurting it. or breaking roots ... its how its done ... otherwise... we need the pic .. once you know what it is. you can probably find videos on how to do it.. ken

Peperomia glabella Looks like yours might have in addition been one of the forms sold as "red stem" or "red stemmed".