Will Eneloop batteries kept in an AA-to-D converter discharge faster if unused?

My mom has a device that takes D batteries. To avoid any leaking, I have replaced the alkaline D batteries that were in there with Eneloop AA batteries using some of these AA-to-D converters:

https://www.amazon.com/gp/product/B074PKPPNS/?tag=cpf0b6-20

I also want to give her some more AA-to-D converters, so that when the batteries run out, she can replace them immediately and continue using the device while she waits for the other batteries to recharge.

Would it be okay if I put 3 Eneloop AA batteries into one of those converters and just let it sit there for a long time without using it? Would those AA batteries discharge faster than normal, or would they continue discharging at their normal rate?

There would be no draw on them if just left in the holder so they should discharge at a normal rate.

If all the batteries are healthy then they should first balance each other out and discharge at a combined rate. If one or two of the batteries have higher self discharge they will be balanced out by the ones with lower self discharge. I would just leave them in the adapters and if they sit for 6 months or longer take a voltage measurement of them just in case you may want to top them off as some devices using alkaleaks tend to not want to work well when nimh batteries drop down below 1.3v or so.