Once all of the segments are where we need them, we are going to smoothen their corners using the Corner tool (shortcut:C). This is one of my favorite tools in Affinity Designer. The live Corner tool allows you to adjust your nodes and segments to perfection. Select it by pressingC, ...
break curve on every node / corner to get lines of 2 nodes now do 4 iterations (one for every edge curve of 2 nodes), use move tool and power duplicate finally, re-combine curves (if required). May use macro. it may be sufficient to break into 2 curves of 3 nodes to reduce effor...
I'm asking because to really depends on those answers to find the best solution. If you do it for your living, many tiles per day: Choose a different app which is better suited to edit curves / nodes, and offers shape builder tools. This is not the strongest part of Affinity. ...