The Orbot currently in Google's Play store appears to be based on Tor 0.2.8.9. Yes, this isn't the newest release of Tor, not even the newest version of the 0.2.8.x series (which is still supported.) The changelog tells me that Orbot is not missing any severe security issues, so you should be fine.
As to why Orbot isn't using the newest Tor version, I don't know for sure, but my guess is lack of time and resources. Take a look at the commit history and you'll see that just one person has worked on it lately.
Btw, there is a newer beta version available on github. So, work to have it updated is in progress.
As with Orbot, Orfox appears to lack (human) resources. It would even appear that the same person that maintains Orbot also maintains Orfox. I looked at the updates and security updates for 45.6, 45.7, 45.8 and 45.9 appear to be missing. This are the security advisory for the Desktop version, Firefox does not release an Android version of the ESR channel, so some vulnerabilities may not apply to Android. Also, Orfox inherits some hardening from Tor Browser, so a few vulnerabilities are likely not applicable because of it. I would appear that Orfox has been updated due to a severe security issues before, take a look at this and this.
All in all, I'd say improvements can and should be made.
I guess, I can't but agree with you that both should be updated. Yet, keep in mind that Orfox, Orbot as well as Tor itself depend on funding and volunteering, so consider supporting Tor. Running relays, answering question on stackexchange, developing software, Telling your friends about Tor and monetary support are all very much appreciated.
And, Yes, Orbot and Orfox should stick to the same release schedule as Tor and Tor Browser respectively. However, I'm still very thankful to the Guardian Project and its people that they provide this tools and I'm sure they are trying their best to make improvements where ever it is needed most.
Out of curiosity, how and when did you try to contact the developers?