I've just submitted v3.4.0 of the Bootstrap-4 template; it's now available for download (https://www.zen-cart.com/downloads.php?do=file&id=2191) and supports the Zen Cart 1.5.7 series as well as 1.5.8!

This release contains changes associated with the following GitHub issues and has been validated with Zen Cart v1.5.8:

#151: Update zen_cfg_read_only, using zc158 version for zc157 change
#150: Remove redundant button definitions
#147: ZcaBootstrapObserver::setVariables incompatible with PHP 8.2's dynamic properties' restriction
#142: Enable additional content to be displayed on the shopping_cart page
#141: Use 'standard' Zen Cart HTML 'id' for cart quantity/button display and centerboxes
#140: Don't include conditions if shipping and/or billing isn't available
#139: Preload (rather than prefetch) the CDN-based css/js files
#138: Consolidate One-Page Checkout/Bootstrap template integration
#137: 'common_address_formatting', set as primary checkbox should appear only for address_book_process
#136: Move 'country' selection above 'state' in common-address formatting
#135: Remove unused template files for all/featured/new products' listings
#135 opened on Jul 18 by lat9
#134: zc158 Compatibility, overall changes required.
#133: Exporting ZCA Bootstrap Colors
#132: orphan statement in tpl_modules_manufacturer_info
#131: modules\bootstrap\category_row.php compare to core ZC158 query
#130: centerboxes\new_products.php comparison to core query
#125: contact_us "Send Email To:" Selection Is Not Really Required
#124: Raw HTML displayed for when customer views an order's history
#122: Restore 'base' Zen Cart attributes HTML class and id attributes.