Most widespread bird to see in park, I would think.
An abbreviated Hawaiian description of this species and its reddish (when new) fronds:
"These red fronds are called Ehupuaa, meaning “burnt/singed pig” (ehu= burnt/red, puaa=pig/boar). Hawaiian stories tell us that this is a sign of a battle between Pele, the goddess of fire, associated with lava and volcanoes and Kamapuaa, the god of the rainforest, associated with a giant boar “puaa” who could take on many forms.
The story says that Kamapuaa and Pele had a bit of a love hate relationship continuously going on between them. It is said that Kamapuaa was often the instigator of their battles. Kamapuaa knew that he could run faster than Pele, so he would tease her relentlessly then run away into the forest, turning himself into the Amau fern to evade his suitor once she followed him into the wood. Sometimes though, Kamapuaa would be a little too slow to change, and Pele would rush right past him, burning him with her fire as she brushed by him and on into the woods. Pele’s intense heat is said to have burned Kamapuaa, forcing him to stifle his screams, lest she actually find him. Kamapuaa would then be left with a searing red fern frond in his Amau form, hence the name Ehupuaa."
From the Hawaii Forest & Trail website, which offered the refuge tour where the fern was observed.
I'm not 100% certain that it's Zizeeria knysna, but based on past observations across the river in Kinshasa, I believe it is a good candidate.
Not 100% sure of Cisticola ID, but it's my best guess.
Perching on ground is a behavior for A. sitchensis identified in Hudson and Armstrong field guide of Alaskan odonates.