Current Status of Electronic Letter of Credit Infrastructure (TSU/BOLERO) and E-NEGO Practical Usage

I am a student studying international trade, and I am posting this because it is difficult to find up-to-date materials and I don't have anyone to ask. If any part of my question is difficult to answer, please feel free to let me know. My questions are as follows: 1) I understand that SWIFT's TSU and BOLERO are infrastructures used for the operation of electronic Letters of Credit (L/C). However, older materials state that BOLERO failed to achieve commercialization due to high initial costs. I am wondering if BOLERO is currently not being used in practical business operations. 2) Older materials suggested that because there was no complete model providing electronic L/C services, TSU needed to be commercialized for L/C operations. Meanwhile, relatively recent articles state that KEB (Korea Exchange Bank) was the fourth in the world to commercialize TSU. I am curious whether TSU is currently being used in practice as the representative model for electronic L/Cs, and if so, whether it is used through global connectivity or if its use is limited to the domestic market. 3) I am wondering if E-NEGO is currently being actively utilized. 4) Older materials state that while several domestic banks use electronic L/Cs, only KEB implements E-NEGO. I would like to know if E-NEGO is still provided exclusively by KEB, or if other banks provide it as well (and if so, which banks). If it is still only provided by KEB, I am also curious if there are any specific constraints preventing E-NEGO from being widely adopted.