#vocoding

No, that was always the case... in fact, here's a clip exchange between Testament and Potemkin from the Drama CDs (echos are enhanced for special attacks in some cases):

Here's a clear sample of Testament's GGX normal voice:

Echoes in Special Moves were more prominent in the original Guilty Gear and Guilty Gear X. After XX and Accent Core, the audio "echo" was less prominent, but the "stereo" vocoder voice for certain characters was still there (Testament, Justice, Potemkin, Eddie, Robo-Ky, and I-No in a rare instance).

And actually in Testament's case, it's the same vocoder "stereo voice" that was used as the Announcer for both GG1 and GGX... which is why the announcer for those games sounds so weird.

It was "intended" that Testament's voice be used as the announcer (system voice) for both games (since they were the mastermind behind the first tournament, but also because they were protecting Dizzy in GGX).

Of course, Takeshi Kondou-san (Faust/Potemkin's CV) ended up being the voice announcer for GGX instead, but he would later go on to do Baiken's Samurai Intro voice and also voice 2Cave in Venom's After Story in XrdRev2.

By and large you're going to get a lot of different interpretations.

But even if you stuck with Ishiwatari's interpretation, he's not the only one who worked behind the scenes on Testament or the other characters in terms of direction and presentation.

Nor is this the only official GG interpretation out there. (Meaning ASW can sometimes make flubs/contradict their own works at times.)

In my case, I am more inclined to believe the choice was made out of respect for the character's presentation (regardless of gender).

Meaning, Testament had a very polite and elegant voice and inflection (even in past games).

What was more significant was the "pitch" of the voice, and the way the voice was presented (rather than what gender you would typically assume it to be).

The Japanese voice was likely chosen to match what Testament originally sounded like... (or as close as possible).

The English voice was likely chosen to fit the nuance of the character as a gentleman (even as a grim reaper). Along with a clean presentation of English dialogue to fit their translation.

Testament's original voice was like a "stereo" of two voices (similar to Fusion voices, like Gotenks or Gogeta in Dragonball FighterZ). The idea was to present two different genders at once (Kum Haehyun is another example of this, though Bedman's distorted voice and Justice' distorted voice also had elements of this).

Dizzy's voice (when playing as Necro) also had elements of this "stereo distortion", though that was later replaced with a "male voice" for Necro in Xrd.

Anyway, if you're asking how I interpret Testament:

In the past 'he' was human, but now 'they' are a complex Gear.

Does that make sense?

Just to give you an idea of how Pitch alteration and Vocoding works on voices.

The first Sample is just the normal English Dub of Potemkin in Guilty Gear Strive as you normally hear it.