Back to the task at hand, note that one of the features of the Rigol is that of Search, where you should be able to search for I2C events, like I2C start, stop, restart, addresses and/or data.
Firstly, Search doesn't even work on the LA channels, quite an omission IMO.
Secondly, Search only seems to work reliably on trivial things with I2C like Start, Stop and restart, and just semi-reliably on Address and/or Data. It seems to work best when you first capture the trace, then manipulate your search on the captured result without Zoom.
Unlike Search, all of these options do work on the trigger (except sometimes on a Data trigger, the scope crashes when trying to assign the Bit X data: at this stage I tend to have to start again with the scope setup).
Note that when triggering or searching on data, byte(s) specified in the I2C packet only relate to byte(s) immediately after the address, although you can use XX for unimportant bytes. This does not help if you're looking for a particular byte at any point in a packet, such as a string search. Rigol is not alone in this, Keysight 3000T also behaves in the same way in search (but you can do this as a trigger). On the Tek MDO3000 & MDO4000 you can both search and trigger on any data byte in the backet being a certain value.
The implementation of I2C search on the Rigol seems to be a bit of a box ticking afterthought, not just in terms of functionality, but also in terms of flakiness, so much so that as soon as you start trying to use it you realise it's of little practical use. Stick to using I2C triggers and the Record function instead!