Three things:
1. That is not the adapter you need to convert an XLR headphone cable to plug into the Diablo 4.4mm Pentaconn. That one is designed to adapt a 4.4mm cable to plug into an XLR output on an amplifier.
2. The same advertisement says this just below the warning you posted.
“ High resolving power, smooth sound transparent, clear and full of layered detail, IF moist, magnetic voice, full of powerful low frequency “
I would not put a lot of stock in anything they say, frankly it is quite apparent that the sellers grasp of the English language is not exceptional. Their warning is technically meaningless.
3. The adapter you do need is extremely simple, doesn’t need to be stated as compatible with portable amplifiers, desktop amplifiers, the Diablo specifically or anything. Just find a good quality one that plugs into the 4 pin XLR of you cable and has a 4.4mm male at the other end.
This is only confusing because you are looking at Chinese sellers on Amazon and making far to much of a warning that makes no sense if you understand what you need.
I don’t know where you are located but buy an adapter cable off a reputable manufacturer with a name that is well know and trustworthy.
Forza Audioworks in Poland are exceptional and have quite quick manufacture and delivery. I have three headphone cables and an interconnect cable from then. They know what they are doing and the quality is excellent. I just checked their site and you can configure a cable under the “Extenders/Pigtails” category. See screenshot below.
There are any number of quality manufacturers in the USA, you would probably find them advertising on this site.
If you want to buy through Amazon I have three headphone cables and a 4.4mm to 4.4mm interconnect cable from GUCraftsman on Amazon and they make excellent quality cables. The below is their short 4 pin XLR female to 4.4mm male headphone adapter cable of the type you need. This would also be an excellent choice.
https://www.amazon.com/Balanced-Portable-Headphone-Adapter-Crystal/dp/B09DFM6955?ref_=ast_sto_dp
Screenshot from Forza page: