So, Batchelor is an important source - a missionary to Japan who sympathetically wrote extensively about Ainu culture and language at a time when the Japanese government was trying to stamp it out, and there wasn't much Japanese interest in studying the Ainu. He definitely wrote down stuff that was being destroyed/lost then and later.

But of course, he's also a guy from the other side of the world, looking at a culture from the outside, not completely versed in their language, and in Japan to replace their religion. Even an outside anthropologist with the best intentions and insight isn't going to get everything right/ preserve the culture and language the way people in the culture understand it.

So, the guy's important but flawed, what can you do with that? If you have access to a good online library/online database, the best thing to do is see what modern scholars and Ainu people have written about Batchelor's work, which combines the strength of his contemporary observations with some modern reflection and current indigenous voices. These resources do exist.

However, if you don't have access to a university-level library/research databases, it's a harder task. I don't know off-hand if there is anything easily available on this subject, though I could look if you're interested.

If you're doing this project for high school, say, and you really can't access other sources, this is not a bad source, provided you explain in your project that some of the information is filtered through Batchelor's view. (and provided you have at least some other resource - don't do a project based off this one text.)

ETA: One bit of advice for working with Batchelor and really all 19th century ethnographers, ignore any theorizing about racial characteristicis and origins. They were working with out-dated racial ideas and limited information, so even when they aren't motivated by malicious racism (which Batchelor wasn't), they end up really off the mark.

Pay the most attention to events and things Batchelor (or others) is describing as having seen with his own eyes, the least attention to hear-say he reports.

These tips won't get you all the way, but they're a good start for dealing with this sort of source.