Current behavior:
It is not possible to use variable length patterns in lookbehind regular expressions for file import settings or in the Editor for Desktop. After file import with using When using Error message that the Regexp is not a permissible regular expression is shown. It does not work in Editor for Desktop either when filtering by Regexp.

Example - does work:

(?<=text).+

Example - does not work:

(?<=te?xt).+

Available workaround (if any):
N/A. The expressions need to be listed one by one.

Requested behavior:
Allow the possibility to use variable length patterns.

Use case:
More flexibility when importing the files or in the Editor for Desktop.