Why does it make it difficult for Ta? TA is a graphical representation of price, if boj is buying $ this will be seen in the chart as a downward trend for the yen.
TA does not drive price, it just makes it easier to see where its been to allow us to come to a decision as to where it might go, followed by where we should jump on board and where we should put our stops.
Sometimes in developing a rule set for entering trades based on ta we get confused and think that that the market should conform with our rule set/TA.
We forget to look at our set ups in context to what is going on in the market, in effect we lose sight of the bigger TA picture.
For example if I trade off support resistance with sound TA and a good rule set I'd still be daft to be buying the yen at previous support levels.
Ramble over
I do use TA all the time for my trading decisions and keep record of the trades. Not long ago wouldn't be difficult to make 10% a week. All that changed for the last 5-6 weeks where I've managed to break even or make a small profit each week. I haven't changed my system, so would think there must be something to do with the current market condition (choppy intra day moves).
PS As a day trader I hardly pay attention to anything higher than 4h charts, so the bigger TA picture (daily, weekly etc.) doesn't help me that much.