It will not undo all of the healing.  If it did, diagnosis of celiac disease would be much easier!  To have enough damage to see on an endoscopy requires several weeks of gluten ingestion. 

HI, I am new to this and am still in 'repair' mode, which I know will take time. But I'm wondering if anyone knows what happens if you ingest gluten after you have made a lot of progress in repairing your villi. Does anyone know if you just have a short-term issue? Or does an accidental ingestion of gluten derail all the work you've done and set you back to square one? Thanks.

Hydrolyzed wheat is wheat protein that has been broken down into smaller components through a chemical or enzymatic process called hydrolysis. This ingredient can be found in various products, including cosmetics, personal care items, and some food products. For people with celiac disease, hydrolyzed wheat is generally not safe to consume because it still contains gluten proteins, even in its broken-down form. Though hydrolysis reduces the size of these proteins, it doesn’t fully remove the components that trigger an autoimmune response in people with celiac disease. In food products, hydrolyzed wheat protein still poses a risk and should be avoided. With regard to the McDonald's French fries, the total amount of hydrolyzed wheat in the flavoring is small, and the amount that ends up in an order of fries is even smaller, and likely below 20ppm. McDonald’s states that the fries are gluten-free by ingredient and free from cross-contact with gluten-containing foods in their dedicated fryers. Third-party tests and statements by McDonald's confirm gluten levels are below the FDA threshold for gluten-free labeling (20 parts per million or less). So, while McDonald’s USA fries may be gluten-free based on testing, some people with celiac disease still approach them cautiously due to the past concerns and individual sensitivities.

Here is an excerpt from this article: https://pmc.ncbi.nlm.nih.gov/articles/PMC82695:   Studies have shown that various peptidases of fungal, plant, animal, or bacterial origin are able to hydrolyze gluten into harmless peptides. According to SDS‐PAGE pattern, proteolytic enzymes hydrolyze gliadins (Heredia‐Sandoval et al., 2016; Scherf et al., 2018; Socha et al., 2019; Wei et al., 2018, 2020). Bacterial peptidase (Krishnareddy & Green, 2017), fungal peptidase (Koning et al., 2005), and prolyl endopeptidases (PEPs) (Amador et al., 2019; Janssen et al., 2015; Kerpes et al., 2016; Mamo & Assefa, 2018) thoroughly degrade gliadin fractions to decrease gluten concentration and influence celiac disease. Aspergillus niger derived PEP (AN‐PEP) were assessed in clinical cases for their impact on modifying immune responses to gluten in celiac patients (Lähdeaho et al., 2014). Guerdrum and Bamforth (2012) reported that PEP addition in brewing technology decreased the prolamin and all of the identified immunopathogenic gluten epitopes in beer production (Akeroyd et al., 2016). On the contrary, many of the recent investigations which employed enzyme‐linked immunosorbent assay (ELISA), mass spectrometry, and Western blot analysis reported that PEP did not thoroughly destroy the whole gluten proteins (Allred et al., 2017; Colgrave et al., 2017; Fiedler et al., 2018; Panda et al., 2015), which indicates that beers treated with PEP are not safe for celiac disease patients. Anecdotally, this excerpt supports what we hear from the celiac community on this forum with regard to "gluten free" hydrolyzed wheat products and that is that some still react to them while many don't.

There aren't good studies that have been done on celiac disease remission, and I'm going from a distant memory of an older post here, but the longest remission that Dr. Stefano Guandalini from the University of Chicago Celiac Disease Center has witnessed was ~10 years, then the symptoms of celiac disease and the damage came back. The real issue though, is that you still could increase your risk of various related diseases and disorders by eating gluten, but again, celiac disease remission has not been studies enough to know what health risks you might face.