Honestly, this sounds like a feature request for CityStrides: to add support for certain unnamed roads. For example, specifically to add unnamed laneways (in OSM terms: highway=service + service=alley + name is null - see https://overpass-turbo.eu/s/1wcL for current map/list of those in Toronto).

As I understand it, CityStrides started as a challenge to run all of a city's streets. Not alleyways. So a decision on whether alleyways should be added should probably be taken by CityStrides.

Until then, you're messing up one website (OSM and its database) to hack a feature onto another website (CityStrides). It appears CityStrides does request you don't do that - see for example https://community.citystrides.com/t/osm-question-streets-with-names-that-arent-really-streets/23023/2 (albeit for the opposite issue to yours) or https://community.citystrides.com/t/changing-duplicate-street-names-in-osm/18952/3 (for whether names in OSM should be modified to fix behaviour in CityStrides).

I'll give an example. A while back, Pokemon GO populated their map of the world from OSM, and set Pokemon spawn points to be in parks. Makes sense because people can go to parks and hang out there. Then people who wanted a spawn point near their house would go on OSM and add a park on their front lawn. Technically a lawn might be greenspace, but on a larger scale, it's pretty obviously misusing the database for your own purposes. Pokemon GO wasn't the only user of the OSM data, and everyone else was getting worse experience.
