Tiddlywiki has an expressive internal language in which most of plugins are written1. This reminds me of Emacs/Vim attitude to extensibility. You have all the power, but only if you learn ELisp/Vim script/WikiText.
None of these languages has any application outside their restricted environments. The knowledge regarding these can be neither transferred in or transferred out. There is hardly any meta tools for this internal language - say syntax-highlighting or prettification tools. In addition, unlike Emacs/Vim, the community size of Tiddlywiki is rather small. The effect of such barriers easy to gauge when you compare the speed at which plugin ecosystem is expanding for apps like Obsidian(which has well defined API in Typescript) compared to that of Tiddlywiki.
Overtime I have gained enough mastery over Tiddlywiki widgets and other quirks. However greater number of community built plugins have 2 fold effect
So less tinkering, more actually writing.