I would not criticise any other poster's English. As long as what they say is understandable it is not my job to correct or disrespect them. Some posts can be very short on detail and we need more to deal with there posts, but if so it should be a friendly request.
To be honest my spelling is not that great but the computer does help when this happens but the key board does also seem to miss the odd letter which is annoying when it accepts what is there as it is another acceptable word even if it does not fit the sentence.
I would hope that any person disrespecting any posts for the English or spelling will be dealt with by the moderators.
I think the message is that most people are asking for clarity in a post. Grammar and spelling are important factors in any language - without them there would be no developed language.
This is a caravan forum and members will be a "mixed ability" group when it comes to the specifics of expressing themselves in English.
If the post is clear neither spelling nor grammar require adjustment and anyone pointing out errors that have no bearing on the "message" are not contributing to the general atmosphere of the forum.
You are dead right about the way "predictive text" or a "spell checkers" can introduce "errors" .
I would prefer to spell "criticise" as you do (criticise) but you may well find "criticize" is the preferred "spell checker" spelling! Does it matter? Everyone knows that you are saying! American spellings are often used in software.
Most errors can be attributed to the "spell checker". I'm sure your use of "there" rather than "their" in sentence three will have gone unnoticed because the word used is correct in a different context.
In the world of a caravan forum clarity rules OK! That's not to say that both grammar and spelling have no place in written English - they certainly do.
A long time ago - think it was in this forum - a member responded to a post with direct criticism of the spelling and grammar used. Nothing about the "message" in the post.
I admit that it gave me great delight to be able to "quote" this post and point out both spelling and grammatical errors within it. That's the one and only time I've felt the need. I can't for the life of me remember the response but I suspect it would be to blame the software.