Number of rows limit in Editable Grid

There is no hard limit, but the performance will suffer very hard as you try to display hundreds of rows.

You will have to find a different approach. Maybe this: https://docs.appian.com/suite/help/23.4/recipe-use-links-in-a-grid-to-show-more-details-and-edit-data.html

Please please please don't do this.  For data sets beyond a dozen or so items, use a filterable paging grid where each row can (individually) be clicked on to open a separated editor, where the user makes, validates, and saves any changes independently before moving onto other edits.  Editable grids that try to do 1000 different things to 1000 different rows are the bane of user experience (and impossible to maintain, unless kept exceedingly simple).