I am tempted to give up on this subject - I can read the Chinese now. However I have sympathy for visitors to Taiwan.
Tongyong does not reflect the way Taiwan Chinese speak (to a native English ear) in many ways - sure some parts are OK - and some parts are BAD. The things said in Taiwan as “shi” or “Xi in hanyu pinyin” are now “si” on the Tongyong signs.
As someone else wrote - 44 is “si si si” in Taiwan Mandarin. But Xindian is “Shindian” to English ear - not “Sindian”.
Tongyong badly screwed up in this area.
Given that Mandarin and English are probably the two most widely spoken languages in the world - if there has to be a new “pinyin” it should use syllables best understood in English. If that is not possible hanyu pinyin is OK.
The most important issue is ONE system. The vocal foreigners seem to forget this in their support of something apart from hanyu pinyin.
The vocal foreigners confuse the politicians when the vast majority want hanyu pinyin. 99.99% want one system - 99.8% or more want hanyu pinyin as that sysem. The Chinese pushing Tongyong are basically saying f**k the foreigners - we know better. These chinese have sh*t for brains.
I guess politics remains more important than reality in Taiwan which is why it remains a country in reality but some vague entity to the rest of the world.
Here in Shanghai they occasionaly deal with Shanghainese (Hu) in romanisation - eg signs in some hospitals. The search for a “pinyin” that deals with many Chinese dialects is designed for failure.