i18n_module_create() builds a translation-module skeleton from a package’s help pages, replacing dynamic install/build \Sexpr and #ifdef spans with {ISEXPR_i} placeholders so a translation keeps matching the installed help across reinstalls.
i18n_module_update() re-syncs a translation module against a newer version of its package: unchanged translations are kept, changed sections are flagged fuzzy for review, new sections are added, and removed ones are dropped.
Help pages are shown in the reader’s language, with install- and build-time \Sexpr values filled in from the reader’s own installation.