I'm in the process of creating a (somewhat clunky) workaround to this for our flora sampling form, which allows the user to update heights and cover % in a grid-like table underneath the repeat.
This relies on creating duplicate height and cover questions for each possible repeat (which will be null-type fields), outside of the repeat. The height and cover values within the repeat then update based on what is entered in these duplicate fields, using a javascript function, or a complex if statement. I'm trying to build a string to reference the correct field based on repeat number (see this post: https://community.esri.com/t5/arcgis-survey123-questions/method-to-build-a-string-to-reference-anoth...), but haven't worked that out yet. Note that i'm still showing height and cover within the repeat in the screenshot below, but I will probably hide these fields eventually.
The summary table species names update using the indexed-repeat function.
In my example below I only have 3 species, i'd imagine that by going up to 50 or 100 performance may suffer (and we'll need a lot of extra fields in the XLSform), but we shall see if this works... Either way it will save time on our current process of scrolling back through each repeat to find the right species..