I recently set up a friends laptop with tweaks to assist their vision impairment. Mostly this involved scaling up elements and fonts, cursor size was not large enough, but I've filed a separate issue for that. Kwin effects for inversion and zoom were greatly appreciated by the user! We had a few problems with some mouse effects:

Mouse Click Animation
On both the users laptop and my desktop(both running Manjaro KDE with 5.10), this effect does not seem to work when enabled and the shortcut key toggled. I added an alternate shortcut (meta+alt+z) just incase it was a numpad issue with the default shortcut(meta+*), seems to be the case. I guess the user needs to be aware that numpad * would not work, and that they need to use their meta+shift+8 to get the equivalent(at least on keyboards here shift+8 is *).

Track Mouse
This one was a bit confusing at first(ctrl+meta). If the mouse is stationary and not being moved the effect doesn't toggle to reveal where the cursor is, once the cursor is moving, the effect can toggle, and if the toggle keys are released while the mouse is stationary, the effect will remain until mouse movement. This behaviour took a while to notice and felt like it sometimes was working and other times buggy.

It also lacked any configuration like Mouse Click Animation(MCA) had for colour and radius/line size. An alternative effect that emitted rings like MCA does from the cursor but on shortcut toggle rather than mouse clicks could work nicely, the current effect design wasn't easy for the user to spot/recognize with their impairment(the overlap from the larger cursor size might contribute to that).

macOS has an effect that if you shake/vibrate the mouse quickly it will grow/explode the cursor size briefly(crisp all the way, so maybe their cursor is a vector graphic?). Compiz has a mouse trail effect. Some sort of improvement or alternative to this effect could be really helpful(I haven't checked the KDE Store, but if the devs might be open to considering an improvement/addition for default distribution of effects to aid with this kind of accessibility that'd be nice :) ).

Zoom and Inversion effects were super helpful for the user, they really appreciate that so big kudos to the devs! :)