Re: WA-H58 lens hood / sun shade
 

At least in theory:

The WA series are wide angle "adapters" and do NOT offer full zoom-through.
The WD series are wide angle "converters" and should offer full zoom-through when used on specified camcorders.

The "H" in the name does imply suitable for HD
An "U" in the name implies suitable for UHD (e.g., 4K)
No H or U implies design for SD video. If used on a HD or UHD camcorder expect the images to be a bit softer.

Further:
The WD-H58 0.7x will fit on the XA20, but will vignette at the widest zoom setting, especially if image stabilization is turned off.
The WD-H58W 0.8x does not vignette on the XA20.
(Note thattheXA10 and XA20 use a different lens and the XA20 is wider, even more so if Dynamic Image Stabilization is off).

The WD-58 (no H or U) was marketed for the GL1/GL2.
I've used a Sony VLC-HG0758 Converter (Marketed for the VX2000) on the XA20 and it is softer than the WD-H58.'H58W.

FWIW: The stock XHA1 used a ~79 mm (measured at the lugs) bayonet-mount lens hood with a window for the IAF sensor at 9 o-clock (as one looks into the lens). The clamp screw is at about 7:30.
The official wide angle add-on for the XHA1 was the WA-H72 per the manual.

The XL1/2 and XL-H1 series offered a separate wide angle 3x zoom lens