If you change key “cycleway:left” for “cycleway”, as it seems you are trying to do, you will lose the information of on which side of the road is located the cycleway. No matter if a key is ignored by tools, if it’s well defined is up to the tools to make use of the information.

Do the change only if you are sure of what are you doing, and it would be better to check with the local OSM community first.