Unfortunately, I believe the configurable text importer also fails in the same way. With the attached .csv file I get identical results either by automatic importation or by using the configurable text importer (setting " as the text indicator).
I think the .csv specification is not the source of the problem, and neither is text importation. The problem is that Gnumeric always interprets a string such as 10.24.2 as a date unless it is preceded by a single quote ' . This is true for either manual (keyboard) input or text import. If I enter 10.24.2 into a blank cell, Gnumeric interprets that as a date unless I precede it with an apostrophe. I did not find an actual specification for entering dates, but the Help document has many examples, and this format (with periods) is not one of them.
For text import this behavior does not work if a delimiter is intended as part of the string. For example, in the attached .csv file, importing the first and second lines fails if commas are intended as part of the string. In the third and fourth lines of the attachment, Gnumeric recognizes "10.24.2, 3.7" as a string, but again it interprets "10.24.2" as a date (use " as the text indicator). For my own application I can work around it easily, but I didn't find a general workaround. To import strings like that I suppose one could use tab-delimited files, but the undesirable effect is that the file import method must depend on the strings.
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test2.csv
Description: Text document