Use the word "retard" as a noun in a sentence in a non-offensive way. Show mw how it can be done.

That's an easy challenge:

...The NOx reduction is effected during the operation in the stoichiometric mode in a previously given speed/torque range by timing adjustment from the point of optimum efficiency in the direction of retard. ...

...Results the results indicated that six different REV strains could cause the retard of growth...

...On the basis of these factors, a possible retard of the start of pump delivery can be determined. By an actuation of a three/two-directional control valve...

or in a music context:

...Observe that onset components of the field may also be negative, according to the retard of onset in the middle arpeggio region of pitch around ...

Even with regard to humans it can still be used as a noun in a non-offensive way:

...The acute malnutrition increased in infants from 12% to 23% and the percentage of children with retard of growth in height and the
overweight, was increased....

And then there are retarded integral inequalities in math...

Now to the short serious part of my post:
The word "retard(ed/ation)" was introduced (by a broadening of its original meaning) many decades ago to get rid of the pejorative connotation of words like idiot, moron or imbecile. Like all words introduced to get rid of such connotations, this word too has failed in that respect for the connotations have now usurped the meant to be innocuous word. And so it will happen over decades with whatever word or expression replacing "retard".

Wolfgang