I had loads of pics on here and done an arm and calf log with syntherol. I used an image uploading website for all my pics on here and a few years ago they randomly closed down their website and it stated all pics will be lost. So pretty much every pic I posted on here for about 10 years were lost. My old phone also broke many years ago so I have no access to them anymore. I had some old pics saved on social media but my before and after syntherol pics weren't something I was going to post on my facebook at the time

I made big changes using syntherol in my arms and calves. It is an amazing tool but like anything in bodybuilding it's not permanent.
The guys who are ruining body parts are putting other things in there. There is a misconception regarding SEO such as syntherol. You don't inject it and it just stays there forever. It doesn't help that all the old pro's lie about everything. Even when the likes of Flex Wheeler come out recently and it was worded like a tell all about his seo abuse etc it was complete nonsense.
Nearly every high level UK bodybuilder is using HA before shows. I am surprised you didn't know this. I literally chat with none of them nor have I any interest in UK bodybuilding and I was told this years ago. Even the bikini girls are using it before shows in the UK. As you stated it's very popular here but so is SEO as well. Maybe they lie to you because they know you are a genuine threat to them winning if they ever compete against you. Obviously there will be many who don't use it but I have been told by people that nearly every athlete they coach is using it before shows.
Even the HA is not permanent either and it dissipates over time. The girl I am seeing has just had 80ml of it injected into her arse from a salon owner. It's not just popular in bodybuilding circles.
It's up to you and if you think you need it go for it. I would need to see pics to best advise you. From memory you are well balanced. Do your arms hold up well during a contest prep? Has a judge ever said you need more size? Maybe you just need more time because you have made amazing progress in a relatively short time so the genetics are there so see where you stand before adding in such measures. Although if something works and you are stood next to guys on stage all using it why not use it yourself.
In regards to health issues and certain well know "SEO users" they are often putting alsorts of different things in their bodies. Take Rich Piana for instance he was full of silicone. He also went to Mexico for PMMA injections as well which was well known but he lied and said it was just to fix a small issue. His ex also stated he had someone who would inject him with silicone and he also made her get it done as well. The likes of this is what is causing health issues because it's just sitting inside permanently. This is what all the girls are getting down in South America (everywhere now).