For some automatic tasks, we would like to know, that the content has been recently modified by the task rather than by an editor user.

To achive this in CMS content one can use IPrincipalAccessor and this works for PageData.
However it does not work for Catalog content (EntryContentBase), and after saving the content, it still uses name of last user.

Package versions:
EPiServer.Framework 12.13.1
EPiServer.CMS 12.17.1
EPiServer.Commerce 14.10.0

Consider following code:

private readonly IContentRepository _contentRepository;
private readonly IPrincipalAccessor _principalAccessor;
private readonly ReferenceConverter _referenceConverter;

// injection omitted for brevity 

_principalAccessor.Principal = new GenericPrincipal
(
    new GenericIdentity("AutomaticTask"),
    new[] { Roles.Administrators }
);

var pageReference = new ContentReference(1414);
var productReference = _referenceConverter.GetContentLink("Product2_1");

var page = _contentRepository.Get<StandardPage>(pageReference); // StandardPage inherits PageData
var product = _contentRepository.Get<FancyProduct>(productReference); // FancyProduct inherits ProductContent

var writablePage = page.CreateWritableClone() as StandardPage;
writablePage.MainBody = new (DateTime.UtcNow.Ticks.ToString());
_contentRepository.Save(writablePage, SaveAction.Publish, AccessLevel.NoAccess);

var writableProduct = product.CreateWritableClone() as FancyProduct;
writableProduct.MainBody = new (DateTime.UtcNow.Ticks.ToString());
_contentRepository.Save(writableProduct, SaveAction.Publish, AccessLevel.NoAccess);

Before running the code, after content has been created by editor:

And after running the code: