HP playback techniques are still set to respond to the articulations in the Legacy Fonts. If you enter articulations in the new SMuFL versions of Finale 27, they have not yet been set t trigger Human Playback to play back.

Finale support suggests loading an articulation library from the legacy libraries and replacing the non-functioning SMuFL articulations with those versions of the appropriate symbols as a stopgap until the new codes are supported in HP.

And where, pray tell, would one find such an articulation library? Do we have to create it first? And why, oh, why, can we no longer position dynamics where we want them? 

And, having created such an articulation library and loaded it in, how do we access it?

… where, pray tell, would one find such an articulation library? …

File menu > Load Library…

In the directory dialog box Finale displays its Libraries folder.

Since you need articulations from the (legacy) Maestro font, go to the sub-folder Maestro font.

… having created such an articulation library and loaded it in, how do we access it? …

Articulation Tool.

Click on a note.

Finale displays the dialog box Articulation Selection.

The loaded articulation library will be at the bottom of the Articulation Selection.

You may have to scroll down to the bottom.

The loaded articulation library does not display at all. All I see is the useless one.

Loading the regular Maestro Articulation Library (I discovered) will not help, first off because the legacy Maestro characters do not display correctly nor does it activate the tremolo.

In fact, I started a new file in legacy style and found that assigning the 8 metatool in Articulations to a whole note produced a pizz sound rather than a trem.

Looks like some work is needed here.

Has Finale 27.1 solved the problem of tremolos playback issue?

I don't know. After it wrecked several of my pieces, I reverted to v.26. May stay there until I or my computer die. ;)

I’ve installed the 27.1 but it seems that the problem is not solved.

Some instruments work in 27.1; others, not.