Here is one example how to use the join+csv node to get your desired output. You have 3 inject node for the value and one inject node for saying your join node to dump the data.
in the 3 inject node with the data a topic is set which match the column names of the csv output.
[{"id":"fbaad31a96c57451","type":"inject","z":"8722e064d8751792","name":"TexInputA","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"TexInputA","payload":"$floor($random() * 10)","payloadType":"jsonata","x":340,"y":120,"wires":[["1f9cf96437593ea6"]]},{"id":"8015d36038f3c535","type":"inject","z":"8722e064d8751792","name":"TexInputB","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"TexInputB","payload":"$floor($random() * 10)","payloadType":"jsonata","x":340,"y":180,"wires":[["1f9cf96437593ea6"]]},{"id":"20ede9e4e9d2f78d","type":"inject","z":"8722e064d8751792","name":"TexInputC","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"TexInputC","payload":"$floor($random() * 10)","payloadType":"jsonata","x":340,"y":240,"wires":[["1f9cf96437593ea6"]]},{"id":"b83b85c312d0266b","type":"join","z":"8722e064d8751792","name":"","mode":"custom","build":"object","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":false,"timeout":"","count":"","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":630,"y":240,"wires":[["5c9727fdd6fa5b32","99fb7732339a93d1"]]},{"id":"d4b12c9b11f15605","type":"debug","z":"8722e064d8751792","name":"debug 12","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":980,"y":240,"wires":[]},{"id":"5c9727fdd6fa5b32","type":"csv","z":"8722e064d8751792","name":"","sep":",","hdrin":"","hdrout":"none","multi":"one","ret":"\\n","temp":"TexInputA,TexInputB,TexInputC","skip":"0","strings":true,"include_empty_strings":"","include_null_values":"","x":810,"y":240,"wires":[["d4b12c9b11f15605"]]},{"id":"99fb7732339a93d1","type":"debug","z":"8722e064d8751792","name":"debug","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":790,"y":160,"wires":[]},{"id":"43b73860a952d7e6","type":"inject","z":"8722e064d8751792","name":"complete","props":[{"p":"complete","v":"true","vt":"bool"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","x":440,"y":360,"wires":[["b83b85c312d0266b"]]},{"id":"1f9cf96437593ea6","type":"junction","z":"8722e064d8751792","x":480,"y":240,"wires":[["b83b85c312d0266b"]]}]