The differences are so subtle in these that unless a significant amount was invested in the arbitrage bot, it is very unlikely it'll be picked up. These unique combinations of complementary/supplementary bets can really be picked out by a human.
The fact that OP can consistently find these odds hiding in plain site should be enough proof that arbitrageurs, including botters, simply aren't picking these things up quickly enough to turn a profit. Hence what I said earlier about a *potentially* profitable opportunity.
I don't see any problems with automation from a technical point of view. This is quite easy to do and small differences in the odds do not prevent you from making huge profits, since the bot can complete many transactions in one day. The main problem is that bookmakers chase and ban all fans of guaranteed bets (surebets), regardless of whether they work manually or with the help of bots.