I tried to install this StarDict dictionaries under /usr/share/stardict/dic/bobotig-en.
While they work with original StarDict software, and also with sdcv, they don't work with qstardict. It seems they are just ignored.
This is because currently QStarDict supports only StarDict 2.x dictionaries, while BoboTiG dictionaries are in StarDict 3.0 format.
If you want to have a Wiktionary dictionary, I recommend you to install the current Git version of QStarDict and use Kiwix Wiktionary dictionaries in ZIM format which are available from here: https://download.kiwix.org/zim/wiktionary/. In particular, the English Wiktionary which you are interested in is currently available as wiktionary_en_all_nopic_2023-07.zim there. In order to install a Kiwix ZIM dictionary to QStarDict, use the "+" button in the "Dictionaries" tab in the settings dialog of QStarDict and select "Kiwix ZIM files" as the file format.
The support for StarDict 3.0 dictionaries has been added to QStarDict. You can try it in the current Git version of QStarDict.