No "master", please...
It seems that quotes are added when a cell text ends (or begins) with a space. Looking into the csvdocument sources (which are used by fpspreadsheet) I see that there is a boolean option "QuoteOuterWhiteSpace" which is active by default. When you open file fpscsv.pas, find procedure TsCSVWriter.WriteSheet, add the line "FCSVBuilder.QuoteOuterWhiteSpace := CSVParams.QuoteOuterWhiteSpace;" after the "try", and add a "CSVParams.QuoteOuterWhiteSpace :=false;" to your project code the quotes will be gone.
I committed an updated version of fpspreadsheet in which the TCSVParams record is extended by the following fields:
TsCSVParams = record // W = writing, R = reading, RW = reading/writing
...
QuoteOuterWhiteSpace: Boolean; // W: Quote when cell content begins/ends with white space.
IgnoreOuterWhiteSpace: Boolean; // R: Ignores white space before/after cell content.
....
end;
As you can see you can also set CSVParams.IgnoreOuterWhiteSpace to true to get rid of the leading/trailing spaces already at reading - then these cells will not be quoted either.
But note that the white-space options do not work for numerical cells since the string-to-float conversion occurs via the standard function TryStrToFloat which does a "trim" (white-space removal) before the conversion.